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Digest on Literature on Dielectrics Volume X (1947)

Chapter: Electrical Properties of Matter

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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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Suggested Citation:"Electrical Properties of Matter." National Research Council. 1947. Digest on Literature on Dielectrics Volume X. Washington, DC: The National Academies Press. doi: 10.17226/9572.
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ELI:C07RTC~ PROPERTIES OF OTTER W. A. Yager Bell Telephone Laboratories, Murray Hi1 l,, N. I. T. Introduction The Subject of the Electrical Properties of Matter is so general and broad in scope that one reviewing it is immediately faced smith the problem of ,.~'ha~c material to include and karat to re ject. This sorting-out process is to some extent inf luenced by the T,ersonal equation and refit ects the reviewer' ~ own interest. In Arriving this section of the Digest ~ an at~Gem~t has been made to mace the emphasis an the physical aspects of dielectric be_ . . . havior Bind on the relation between dielectric behavior and structure. The various aspects of microwave technology are also Stressed in view of the nearness of this flied and the growing interest in di- electric investigations at micro rare frequencies a - The volume of literature on dielectrics and related sub jects for 1946 was ~ arge. Research and development in this field was stimulated and actively pursued during the ~.~ and many laboratories and industrial concerns are continuing their ir~ves&Gigations on a peace_tirne basis. A considerable amount of classified material accumulated during the war was published in 1946 but much still remains in as yet unpublished reports. Several dielectric symposia were her ~ last year. The London branches of the Royal Institute of, Chemistry and the Institute of Physics held a Joint meeting aid the Royal Institute on March 20th at which 'Ghe fields of physical theory, chemical re~arati on and industrial application of dielectrics severe broadly surreys The Fawaday Society sponsored a symposium on dielec- trice at the Wills Physical Institute at Bristol, April 24-26th. General surreys and many original papers on the present state and immediate trends of ~hysical-chemica' and physical research in dielectrics severe presented at this meeting. A very good re- sume of these two meetings entliled Dielectrics in Theory and Application appeared in Nature. New Dielectric and Insulating Materials in Radio Engineering was the topic for discussion at a meeting of the Patio Section of the Institute of Electrical Engineers (London) on May 2Ist. A retriever of this discussion on near developments in Plastic and ceramic dielectrics appeared in Engineering and also in Engineer . Three dielectric symposia revere held in this country. Five Scrapers , Plastic Compositions for Dielectric Application,, High Dielectric Constant Ceramics, Paper Capacitors Containing ~ ~ _

ChIorinated Tm~regnants, Dielectric Constants of Dimethgl Silo- ~ane Poly!ners, Id Polystyrene Plastics as High Frequency Di- elect~ice, 'were presented at the April Meeting of the American Chemical Society at Atlantic Giber. This program was ranged in cooperation High the Committee of Chemistry of the Conference on Electrical Insulation, National Research Council. The newly organized Electric Insulation Division of the Electrochemical 130cielg~ sponsored a symposium on New Plastic Insulators at the Both General Meeting of the Society at Toronto, October 16_19th at which the following papers were presented: Thermoset~cing Vinyl Polymers (90~9), Molding Material preforms at Radio Frequencies (90-13), The Dielectric Properties of Phenolic Resins and Molded Compositions (90~3), Introduction to Silicon Che~nistr~r (90-18), Silicones as Electrical Insulating Materials (90_16), Properties of PolYtetrafluorethyler~e of Interest to the Electrical Industry (90-15), Polyethylene (~36 ), The Q-Me~Ger f or Dielectric Measure~nenta on Polyethylene arid Other Plastice at Frequencies up to 50 me/sec. (90-~), and Styrene Copolymer Solvent Reacting Varnishes - Foaterite {90_24~. The Preprint number is given in arentheois. These papers will be published in the forthcoming Transactions of the Electrochemical Society. The conference on Electrical Insulation, National Research Council has resumed its activities by ho1 cling a meeting at Baltimore, November 7-9th. The papers user e divided into two groups: one dealing ·.'rith Progress in Fundamental Research and the Development of blear Materials, the Decor High Measurement Technique and Application of Dielectrics. The first group in- cluded: a survey Aver on Dielectric Constant and ~e followed by papers on Selects ve Absorption of Microwaves by Polar Stators, d Dielectric Absorntion of Solutions of Electrolytes in Solvents of Lo`' Dielectric Constant; a survey pacer on Ferroelectric Dielectrics followed by Darers on Development of Titanta Di . electrics, and Barium Titana~.te and Barium Strontium Titanate as Non-Linear Dielectrics; a survey paper on Plastics with papers on Solvent Reactive Astonishes, Silicones, and Teflon; and, a survey paper on Conductivity and Breakdown with papers on Electro~Che~nical Breakdowns of Boo id Insulation, and Conduction and Bre~Xdo,~ in High Vacuum. The second group consisted of 19 pacers as follows: Dielectric Constant and Lo98 Measurements from ~ cycle to Shiv cycles; two papers on Dielectric Measurements at Microwave Frequencies; Modification of the Resonant Cavity Method for Dielectric Measurements at a Fixed Frequency; a Resonant Cavity Method for Dielectric Measurements at 300 mc/sec.; Dielectric Heating- The Measurement of Loas Under Rising Tem- perature; Electrical Identity Test for Plasticizers of the Type Used in Polyvinyl Chloride Plastics; New Instrumentation and Uni_direction Direct_Current Measurement; The Significance of Current_Time Curves in Determining Dielectric Properties; In- -aulation Resi=tar~ce Measurements smith Particular Reference to Charging Currerit Errors; Use of the Scale Model Method in De- termining O,rerheat~ng of Cables; Corona Starting Voltage Measurements' a survey Hater on Developments in Microwave Cables; a survey Baser on Technic ques and Problems in the Production and Development of Condensers; Effect of Asphalt as a contamination - 2 -

in Oil and in Impregnated Paper; The Use of a Redid D.C. Life quest in the Evaluation of Capacitor Paper; Vitreous Ceramic Compositions; Ceramic Sheet Condensers; and Righ Altitude Flashover and Corona Correction on Ceramic Bushings. Abstracts of these Daters will appear in a forthcoming report of the Conf erence . ~ ' ~ A few parers have appeared dealing with liquids, ionized . gases, crystals and metals. The influence of the concentration and mobility of ions on dielectric los s of ~ nsulating oils has been investigated by Rang . Re concludes that provided there is no dipole loss, the relatiorlship between dielectric loas, W. and viscosity, I, of an insulating oil may be exceeded as log W = A-B log, enrich points out that the mobility of ions is an important factor in the di- elec1;ric loss of an inking oil. Thermal agitation, which causes further dissociation of the oil, increases the dielectric 1 oss by increasing the number cuff ions present. The addition of deteriorated oil rabidly increases the dielectric loss thus shoaling that this ~ oss is a function of the concentration or content of free ions in the oil. An increase in the concentration of ions in en oil may result in a critical decrease in dielectric Toss it the viscosity is increased to the point where the mobility of the ions is decreased relatively more than -the ion concentration is increased. Finally, it is concluded that if non-~ol ar oils of the same degree of "electrical purity" are used for low frequency applications where the floss of the liquid is unimportant, the of] of higher viscosity is ,3refera~b~e from the standpoint of poorer hi electric los ~ . Gonick6a has obtained data for the osmotic behavior, conductance, bend relative viscosity of solutions of hexanolamine ca~r~ylate and diiso~ro~y~amine crate and has determined the concentration of free cations in the former Re concludes that hexanolamine carry ate associe.tes fire t ~Q neutral ion pairs f°~°~b by secondary association to col~oid. In a later cater, Gonick conceders the relation between Stokers law and the imiting conductance of organic ions. Equations are proposed for expressing the limiting ionic cor.ductances of organic ions in terms of CHUB groups cr their equiva:1 ents for monobasic and dibasic ~.li~hatic carboxylic acids, ali~hatic primary, secondary and tertiary am.ines end ali~hatic divines. Hydration through hydrogen bonding increases the ionic conductances as a result of the reduction of the van der Cal' s radius of the group in- ~ro~ red . The effective " spherical volumes " as Cal cul ated by Stokers low severe founcr to agree Cal osely with the volumes cal- culated from. independent date., and are 'Ghought to be a~croxi- mutely the same as their true ~rolurnes. With other series these values differ from the true volumes. The limiting cor~ductances of severer alkyd cerboxylate ions vrere calculated .! ma- method corps proposed for determining the en,3rox.ima~ce CH2 eoui~ralents of - 3 -

substituted methyl enes anci ethyl enes . The electrical conductances of aqueous solutions of r~ote~sium meta~eriodate and potassium r~errhenate were measured by Jones7 over the concentration range 0.0004 m to approximate s~.~uration. The lin~i~cing conauctences were determined by three tr~ecendent ~r.ethod.s with sP~tis~actory agreement. The limiting cond~'lcta~.ces of the anions were determined by use of the reco-^ded revue for the K ton e.ncl the ~.e~sured values for the salts from this in~resti~P.tion. The values acc elated for ~0 are 127.90 for the metP.r)eriodete and 128.20 for the ~errhenate with an accuracy betided to be ~ 0~07 conductance unite. The fol~o:~ng values f or the 2nobilitles ,~rere obtained: metaneriodate ion - 54.38 0~07 ond ~errhena~re ion - 54~68 ~ .07. P!alstion and '-oerr8 have investigated the electrical conductivity of hexed _ and dodecyl _ arnn~onium chlorides in pure coaler, pure ethanol and in various concentration of aqueous e~ch?.nol. The ads it' on of ethanol to aqueous solu~Gi one of he~:yl- em-.oniur~ chloride ].o~Ters the conductivity at all concentrations investigated. The conductivitles of concentrated soluti one of dodecylam~onium chloride are increased by the addition of small amounts of alcohol. The addition of alcohol to more dilute solutions of this salt 1P accompanied by an irregular decrease in the conductivities. The difference in behavior of these two salts is ascribed to micel le formation in solutions of dodecyl- ammonium ch1 oride. Mlcelle Coronation is completely inhibited by the addition of large amounts of alcohol. The behavior of these salts in the solvents used is discussed in the light, of the present micel le theory. The formation of ionized water films on dielectrics under-condition of high humidity was studied by Field e Wher. a dielectric is placed in a saturated atmosphere, art ionized film of fretter forms on the surface whose conductance at the er] of one minute is Thin a factor of 10 of its equilibrium value which is usually Chained in an hour. This ea,uilibrium con- ductance ranges from loo micromhos for. ordinary glass and quartz to er,~roximately zero for silicone resins, silicone _ treated g1 ~ n and hydrocarbon pries. Time _ rely curves are shown for Polystyrene, Polyethylene, quartz, mica and asbestos filled ohenolics, polyamide, s'reati~Ge and mica. Ce7llllose acetate butyrete ~neint~-ins ~ high resisti~ri~cy even after at'_ sorbing a~ rater. The ~e~axatior~ frequency for dielectric Colors zatior~ shears to be in the audits e range . Chau~hur~; ~ studied the effect of the change in the concentration of Acne near the electrode surface upon the corl- ductivities or mobs ~ ~ ties of lone in strorl~ electrolytes and deduced an equation for the conductivity of electrolytes. It is shown the t Onnager' s equation is a limiting equation for low concentrations of electrolytes, lower voltages and high frequencies The variation of the c~nducti~rity Keith varying voltage and con- centretions and ureter dirferen~c conditions is discussed. - 4 _

Fox\} investiga~Ged the effect of ultrasonic waves on the conductivity of Bait solutions. Adiabatic compression raises the conductivity of an aqueous sal1; solution because of direct pressure influences and of increase in temperature e An ultrasonic A. wave, therefore, modifies periodically the conductivity of the medium. If a filament of current passes normal to the wave prom r~agation, the Brave train produces under proper conditions an alternating potential Rich can be picked up. A convenient re- ceiver can be constructed which indicates absolute intensity and can be used for the investigation of ultrasonic fields in water provided the frequency is not above ~ .5 me e Ogg has reported a new effect in metal_am~nonia solu_ lions which is a~eribed to the Physical interaction of electrons with liquid dielectric media. Re found that extremely dilute liquid asnmonta solutions of metallic solid show a marked in- crease in electrical! conductivity upon irradiation ~.~rith visible light. This effect was observed in the temperature range _35 to -7500. and the phenomenon is discussed ore the basis of quantum_ mechanical considerations. The absorption spectrum and magnetic susceptibilities of meter ammonia solutions are in at least quali- tati~re agreement with theory. In a second paner, Ogg)3 outlines briefly the theoretical considerations which preceded the e~eri- mental discoveries relating to the properties of metal ammonia solutions. Weissm.an has observed the de~x~ase in resistance enrich occurs when a solution of sodium in ~i.quld ammonia, in a concentration range which yields two liquid phases, is rapidly frozen as reported by C}gg. Rapid freezing of solutions of methyl_ amine to which several per cent of ammonia has been added seas found to produce similar changes in resistances When a 0.05N solution of potassium in JO to ~ methylamine ammonia was rapidly chilled. frown 260 ° to 90° E. and then "heal edit at 1 70°E, the resistance propped from a Prague of 700 ohms at the highest Hem_ - Erasure to a steady value of OR ohm in the solid state. The changes in the electrical conduc~Givities arid vis- cosities smith temperature of the negatively charged colloidal solutions of ferric venede.te' mo~ydate,, tunstate, borate, ar_ senate and phosphate have been investigated by Mushran and Prakesh\S. The temperatures of zero conductance of the vari our solutions have been obtained by extrapolating the conductance versus temperature curves to zero conductance. Values lying between -16° and -2~3~5°Co were found. The temperature coeffi- ciente of conductivity of the various solutions have been ce.~- cul ated and it is observed I the values are a] ''rays ~ es ~ chart 2< of the conductences at 35°C. The temperatures or infinite viscosity for these solu~Gions were ~ike~.rise obtained by extra_ Orion of the inverse viscosity versus temperature curves. These temperatures lie between _17° and _28°~. It is concluded that the temperatures of zero conc~,uctance of the various solutions . ~ are nearly the same as those of infinite Viscosity. I:x~eriments on the Hill effect by Kelabukho~rl6 show - 5 _

that ~ crystals saturated stitch iodine possess an electronic conductance. A mechanism of such a conductance is suggested Tuna is used to explain previously observed results for KI crystals in a strong electric field. The electrical conductivity of. twenty singe e crystals of SiC have been measured by Busch A sensitive null method using a Alfferential gal manometer loran used to test Ohm's law. For currents between 10-5 and a~nroz:l- m~te 1 ampere per sq. cm. t the law was found to hold within experimental error. No volume rectifying effect was observed. A vacuum tube voltmeter was used. to measure the temperature dependence of the cond~ucti~rity between 80 and 1400°E. Both the conduc~Givi~cy and the temperature variation are re~roclucible for the same crystal but wlae hart ations were observed be~c~'een dif- ferent crystals At room temperature, the conductivity varies between 5 x 10-13 e.nd 5 reciprocal ohms/c!n. At high t.emcerature, the conductivity goes through a maximum. At sufficiently low temperatures, t,`'o temperature regions were found in ditch log conductivity is a linear function of the reciprocal temperature, the Diodes of the lines in the two regions being different. The theory of disordered crystal ~ is applied go the semi_conductor problem . Morton)8 demonstrated that cat culation of the ioniza- ~cion current in a gaseous discharge by means of the classical Townsend equati on is likely to lead to large errors when the field distribution is non_uniform. A differential-difference equation for the electron current as a function of the electron energy aria distance from the cathode is derived an, the ioniza- tion current is calculated for ~ restricted range of pressure and applied frontage. The results vrere found to agree with neesurea current Are thin the range There the assumed functions apply. The conduction and dlsoersi~n of l onlzed gases at high frequencies were studied by Margenau 9. Re derived a distal_ button 1~w for the energy of electrons in a high frequency electromagnetic fl eld by kinetic theory methods. By means of this la1'`7, the currents density and the complex conductivity are calculated as functions of electron den.si!X treasure and fre_ quency of the field. The real Cart of the conductivity has a maximum for gas pressures or frequencies such that the mean free path of an electron is approximately equal to the bellow of the field. From the complex conductivity the dielectric constant of the medium, its index of refraction and its extinction co_ efficient are deducecl. The results are applicable in micro- ~ra~re res earche ~ and in ionospher e ~rob] ems . Although perhaps a little far afield from dielectrics, the electrical resistance of metals at high frequency is never- theleas an important consideration in the design of high frequency test equipment. The electrical resistance of iron wires =d ermalloy strips ~,rere measured by Smith20 and his collaborators ire the frequency range from l.5 to 6 me. Empirical equations

obtained are compared With ex' sting theoretical equations derived on the assumption of constant permeability. Pip~ard2) determined the skin resistance, R. of suora-conducting tin and mercury at a frequency of 1200 me. relative to Rn for the normal metal Just above the transition point. A plot of R/Rn is given for both metals in the temperature range 2.0 _ 4.2°~. This ratio is less than 0.01 for mercury all 3. 7°K . , and for tin at 2.6OR ~ and ri ses steeply to ~ . O at the transition temperatures ~ Partington22 has prepared electrets by allowing different types of dielectric materials to got ~ dify in a field of a~proxi- m~tely 10,000 v/cm. bet~.~reen into parallel metal electrodes, the vo] tage being maintained f or about 2 hours. Measurements of both the anode and cathode surface charges were taken from time to time using a Lindemann electrometer. Typical charge-time curves for electrets prepared from4G~ro different grades of prime yellow car- n?~be. wax, from rosin, and from a mixture of rosin~and carnauba wax are shown and d! acumen. IT B. Dielectric Constant and Dielectric Lose A number of papers appeared last year dealing with din en echoic logs mechanisms and the dielectric ~?ro~erties of Sari ous gases, liqulde and solids. Many of these fall into the categories covered by other sections of the Digest and hence are omitted here. Some of there, hoverer, particularly those dealing ~.~rith the di- en ectric behavior of the ~citanates, represent important contri- b~ions to the uncleretanding of the correlation between dielectric properties and structure. In such cases, it was considered worth_ . 'Chile to risk duplication and retried the more important conclusions troth the emphasis ple.ced on the ch~rsical and st~c~cura~ aspects of the investigation. Gros s and Denard have shown by curves, that ~ permanent charge may be of carnaub& wax by charging it at an e] cooling to R 1 offer temperature. _ ~v ~ is reco~rerer1 which cou15 be stored at the Coverer temperature, the remainder being "frozen in". By mear~s of a graphical analysis of -the d~gche.rge course lt curves using the method of Cole and Cole, Field shows the t the temperature coefficient of all three Earl 7,ati on ~era.meterS ~ - change in dielectric constant, relaxati on tine and storage coeds ici ent are all ~o~iti~re. This beha~rio~ is in c ~n~crast to corresponding negative values for morn! dipol e pol ari _ 7.~' one. Similar experiments with capacity ~ made of oil-fir led Barer, glass, steatite, and mica liked shower ~ positive tem oe~ature coefficient of dielectric constant and a "frozen in'' charge ',hen the color is cooled. Field concludes that it seems reasonable to expect similar behavior for ocher material s in 'which the in~ertaciP1 type polarization is important. means or current-time savored in a capacitor Bade evated temperature and then On discharge. only that charge vitro ev and Jurevich24 have modified Debye's dispersion fr3rmu1?.s to take into account the inertia of rote-~Gion- vibrational _ 7 _

notion of dipole canticles. As a consequence, the electrical con- dUCtlYity yes through ~ maximum which increasing frequency in- stead of approaching a limiting value as required by the formulae when the effect of inertia is neglected. Snoek and Pre 5 describe the atter_effect (relaxation) phenomena enrich are the cause of the d' en ectric losee.s in dielectrics and of at leapt pert of the 1GSSeS in ferromagnetic substances. The close analogy and the connection beeper el ectrice.1 and megne~sic aft~er-ef~ect <end the ~her~omena of e? fistic a.fter_effect ore pointed out. Hector and ,toernley26 here measured the dl electric con- ~12nt 04 eight gases using a heterodyrle beat frequency method. Special Precautions were taken to improve those minor defects in the equipment that are bel'e~r~ci to have contributed to the dif- ferent values obtained by other observers. The At electric constants of the methanol_~.rat~ system from 5 ~ o 55 °C ~ ,~rere measured by Albrig;h t 2- nd Gos tiny Hi th an A.~. bridge circuit to an estimated accuracy of one part in 1000 or better, based upon the assumption that the dielectric constant of strafer at 55aC. in 73.48. The authors report that their values differ consid.era.bly from those of Akerl~f. The red ation between the d' electric constant and the electrostriction of solutions of electrotype es was investigated theoretically by Davt',an28. The variation of dielectric constant was found to be proportional Go the electrostriction. The value of the electrostatic saturation den upon the square of the effective electric field of the ions and also upon the external field. The dielectric constant of diluted solutions appears to be proportional to the concert_ "ration. The proportionality coefficient characterizes the amount of el ectrostriction. Cooper29 describes a series of measurements on solutions of sodium chn oride in distilled Beater over frequency ranges O.g5_13 end 6gO_4320 me. The results are discussed in terms of the Debye- Falkenhagen theory of el ectro~ytes and the available data on the absorption band exhibited by strafer in the region of l°1°°° me. A corn~nris on is made 'pith the published results on the electrical properties of seawater for frequencies up to 10 me. and deductions are made e~s to its probable behavior at Mercy high frequencies. The electrical conductivity loran measured in the freouer?cy range 0e 95 t;0 13 Tic e while the dielectric constant and attenuate on co_ efficient flare measured at frequencies between 690_4320 me. The measuring techniques are described. Schallamach30 published ~ paper on the dielectric re- laxe.tion and viscosity of a number of long-chain Bipolar liquids. Mee.surernente were made in the frequency range 95 kc. to 268 me. and in the temperature range between about -190° and +50°C. En relaxation time (<r) and In viscosity (~) are plotted es functions of reciprocal abeol ate temperature Tt loran found that the acti- vation energies of fir and ~ for these long-chain liquids are not general ly equal except at low temperatures ~ ~ n contrast to the

behavior of liquids of low molecular Freight. The relation between ~ and ~ depends on the nature of the Bipolar group. In mixtures of geranio! and medicinal naraffin,.t is little changed over that for Sure gerantol despite a nine fold increase in ~ at _27°C. In mi';- tures of geraniol in n-he~tane, it was observed that ~ and ~ de_ grease but there arrears to be no correlation in the activation . energies deri~red from the data. In these mixtures, ~ is not as decisive a factor for ~ as would be expected from Debye8s theory. One conclusior~ is that the mechanism of viscous flow of these long chain alcohols changes with rise in temperature. '2 ~ Osiers has applied the Onsager_Kirkwood theory of di- electric polarization of polar liquids to solutions of Solar molecules . A correlati on parameter, Ashore value differing from unity is a measure of the hindering effect of a molecule on its neighbors, is calculated for Solutions of polar molec ales in non- nolar solvents. This parameter is a direct measure of the extent and nature of molecular association. Al ~ of the systems examined shower the same general behavior: parallel association of dipoles in solutions of large concentrations of the polar components and antinarallel association at some lower concentration. At extreme- ly dilute solutions, the dipoles become free of each other. Low- ering the temperature enhances both parallel and antiparal~el associations, the latter arrangement becomes more Pronounced at lower concentrations. Low concentrations of ~Tari¢~us polar mole- cures in crater generally alter the dielectric constant of the crater in a predictable manner. However, dioxane lowers the di- electric constant of crater much more than predicted by theory, indicating strong interaction with water. The variation of the dielectric constant of the nl-ohase of p 9 ~'~azoxyaniso] by magnetic fields has been investigated by Maier32. The change in dielectric constant in longitudinal (I-) and transverse (T) magnetic fields up to 5000 gauss wee determined and it was found that the ratio T/L is not -~/2 as predicted but rather -~/10. By means of X-raya, it is demonstrated that phi a difference is due to orientation in the field free state which in turn is largely due to convection currents. A horizontal tem_ Erasure gradient of O.Io/cm. produces almost complete rotation. This result invalidates existing data on the dielectri c constant as evidence for or against- the Disarm theory. The basic aesump:tion of the a warm theory that the normal state of a cl-~hase is com_ repletely random is not yet Proven. Several comprehensive Caners have been riven ~ eel ing with the dielectric ~ror~ertieg of solic dielectrics. One of these is the contribution of Severs 3 whose gaper on the Relation Between the Po,¢-er Factor an] the Temnera~Gure Coeffici ent of the Dielectric Constant of Sol ice. Die, ectrics consists of five carts Gevers has measured tan ~ and Ac (temperature coefficient of capacity) or At (temperature coefficient of dielectric constant) for a number of solid dielectrics over a aside range of tem~eratur and frequency . Thes e me&suremen~Gs hare shown that in general die' ectri can having a large T.C. (tem~era~Gure coefficient) also _ 9 _ e

have a large ~ra3..ue of tan ~ whereas dielectrics having a small T.C ~ al so hare a small value of tan ~ . A remarkable fact is that the ratio of An to the value of tan ~ at a given temperature croci frequency is nearly the same for most Delia dielectrics. At 20°C. and over a elide range of frequencies, the fold owing re_ Cation was found to hold: And Ac - 0.06 tan ~ . Gevers points out that it is impossible to explain this behavior on the basis of existing theories . In Part ~ of thi ~ report a summary is given of several well knows. theories concerning the causes of the dielectric loa ses and A£ of ionic crystals . Arguments are given to show that these theories are not able to explain the above relation and must, therefore, be replaced by a new one. part T] given a critical Luminary of avail able data in the liter- ature on tan ~ and Ac or A£ restricted to solid clielectrice and radi o frequencies. As far as doe sible ,, the causes of the di- electric losses are inclicated. From this summary, Severs con- cludes that the data found in the literature is not affrays re_ liable and is insufficient to check adequately the Proposed relation bet~reer~ AC and tango Revere, therefore, found it necessary to repeat all measurements as a function of temperature and frequency. Part ITI explains Severs' never theory about di electric losses and the temperature coeffici ent from 'which the proposed relation above follows in a natural prays The negative T.C. of some dielectrics (i.e., TiO2 and polystyrene) is ex_ claimed from the fact that these solids either have a high di- electric constant or a high temperature coefficient of thermal expansion. Another conclusion from Ge~rerst theory which is confirmed by experiment is the existence of a similarity Grin_ ci~le. Finally in Part TIT some remark" are given concerning the dielectric Properties of mixtures of dielectrics. The method of measuring tan it and A£ of dielectrics and the apparatus used for these measurements are described ~ n Part TV. Sources of error and the corrections to be applied are indicat,ea. With the ap- naratua described, the Ac of condensers up to 1000 muff. can be measured at a great number of frequencies in the range from 100 kc. up to 40 me. and at temperatures ranging from 90° to 450°R. The results of ten S and As measurements as a function of ~ em~era~re and frequency are given in Part; V. For some . - materlals the results are treated in detail. The effect of admixtures of a small amount of a foreign substance on the di- e'ectric losses is described. It is shown that al ~ the reach FIGS of the experiments are in accordance with the new theory. Es- Specially the result that the ratio of Ac to ten S has a definite value (~..bout 0~06) for many dielectrics is of particular im- nor~Gance. Tt is pointed out that the nature of the dielectric loss mechanism cannot be deduced from the measurements of tanS and As only; kno'viedge of the chemical composition and the structure of the substance under consideration is inflisnensib~ e . Quartz, mica, various glasses, porcelain, mycalex, marble, ebonite, wood, celluloid, Philite, Pertinex and ~Tovotext are among the materials studied. A reader by StAger34 and his associates deals with _ 10

organic insulating materials in electrical engineering. This Her is primarily concerned ''rith the die1 ectric properties of larnina1;ed structures . The Jie1 ectric ~ronerti es of d.ipolew solids is discussed by Fr~hlich35. Ball a36 found that the di_ electric constant of cotton fibers dried at IGO°C. is about 6 and 3 in the longitudinal and transverse di Sections respectively. Measurements were also made as a functi on of moisture content in both direct) ons un to about 105 of the dry weigh1; at 100°CO .. The experimental procedure and test equipment are described. A short table of the 60 cycle poorer factor at various temperatures from 20° to 100°c. and of the dielectric cores Ant of various materials alas Published in the Electric li~orId~ ~ ~ Schallamach38 reported dielectric dispersion in crys- ta1line aii~o~ro~yl ketone. Data are given for the dielectric constant of this material at lol2 mcO an] 20.4 tic. and for the dielectric loss factor at 1.12, 4.4 and 20.4 mc. over the tem_ erasure range _150 to +20°Co When Roaching the M.P. (-72~5 to -75.5°C.) from higher temperatures, both ea and £~' increase, the rise of £~' indicating incipient anomal ous dispersion. The iallid sunerc cola generally to about -80°C O an] then crystal_ lization is accompanied by ~ sharp drop in c' to a value enrich is still appreciably higher then the optical Braille arid is Be_ Dependent on frequency. Anomalous dispersion is observed in the crystalline state as evidenced by loss factor maxima. It is tentatively suggested that branching of the molecu] e causes a crystal lattice somewhat looser than that of straight ketones and thus reduces the in~Gra-molecular forces sufficiently to allow restricted molecular rotation. Mason39 has nerd the elastic, ~piezoelectric and d' electric constants of NR4H2PO*(ADP) and KH2PO`(KDP) crystals through temperature ranges dn;~m to the curia temperatures. The dies ectric properties of KDP agree Well Irish the theory pre- sented by Sl&ter based on the interaction of the hydrogen bonds Perish the PO4 ions. ADP undergoes a transition at _125°C. at *which the crystal fractures. This transition is probably not connected enrich the H2PO~, hydrogen bond system which controls the dielectric and piezoelectric properties for these lie on smooth curares Rich do not change clone as the transition is encroached. It is suggested that two separate mnd independent hydrogen bond systems awe involved in ADP. The transition axed specific heat anomaly appear to be connected witch hydrogen b ond ~ be Aloe e n the ~ and i: he ~ of the PO. i on s Forte r e as the di_ e' ectric and ~ie%oelectric properties are control 7 ed by the }I2PO4 hydrogen bonds. Mason O has also investigated the elastic ~ niezo- electric and die: ectric properties of sodium chlorate arid sodium bromide otter ~ wide temperature range. At high tem~era~Gures, the dielectric end ~iezoelectric constants increase and in- dice.te the presence of a trans~ormati on point; which occurs at ~ temperature slightly higher then the melting point. A large _ 11 -

dipole piezoelectric conste.n'G (ratio of lattice distortion to dipole ~olexiza~icn) results for these crystals but the elect~o- mechanical coupling factor is small because the dipole polari- za~ion is small compared to the electronic and ionic polarizations and little of the applied energy goes into orienting the dipoles. Tile tem~e~a~Gu-~e variation of the diet ectric constant can be ex- ressed by the empirical vacation: = 4.7 + 3~0 _ 67 50 for NaClO3 320_0 ~ 320-0 ~ 2 and ~ = 4.87 ~ ~, for NaBrO3 where 4 is the temperature in °C. The constant term which is independent of temperature is ascribed to electronic and ionic polarization while the temperature variable term is attributed to changes in orientations of dipoles or the displacement of loosely bound ions such as exist in glass. 4' The paper by Navias and Green ~ on the Dielectric Pro- pPrties of Glasses at IJltra_High Frequencies an] their Relation to Composition will no doubt be reviewed in sorrel detail in the section on ceramic insulation. However ~ in view of the court ration between die] ectric properties and structure inherent in this paper, it is likewise included in this section. The di- electric constant and dielectric loss of 104 glasses of a wide range of compositions were measured at wave_lengths of 10 and 3 by the resonant cavity method. By correlating the power factor data with glass compositions, there is proposed a qualitative explanation of the mechanisms producing energy absorption and diel ectric losses in the microwave range. These mechanisms are Determined by the nature of the bonds Joining the atoms and ions in the randomly orientated atomic networks. The rigid and con- tinuolle networks of SiC a and B O3 glasses are relatively trans- parent to cm. wavelengths energy absorption and diel ect ric losses are low. Addition of network_ modifying oxides yields glasses of greater energy absorption owing to the oxcillation of the interstitial ions thus produced. Increasing the content of any one of these ions results ire higher losses while the co- e:s<:iatence of a variety of these ions generally results in lower losses. Alkali ions glare rise to high losses which increase with ion concentration. Glasses containing a combination of alkalies show lower losses than the equivalent compositions with only one alkali. Bivalent ions do not contribute as much to losses as alkalies but high power factors are shown by glasses Edith high 3~0 or Pb: contents. Dissimilar interstitial ions interact in ultra high frequency fields and thus reduce energy absorption. The losses of high PbO glasses are talus reduced by alkalies and, on the other hand, the presence of RO lowers the losses of glasses containing RHO. Dielectric losses are in- creased by p:LsO3 in much the same manner as by other network modifiers. _~

The unique dielectric behavior of the alkaline earth tita.nites wee discovered Just prior to the Alar. Preliminary experiments indicated may commercial a~licationsO Consequent~y9 the investigation of this group of dielectrics loran greasily in- tensified during the war and Bras placed in the category of c]~.sified material. Noes that restrictions have been lifted, the resul~Gs of these in~reetigations are being Published. Se~rera.l Seders appeared already in 1945 and at least six different irl- vestigations reported the results of their work during 1946. Among those contributing capers last year are P~G{eSSOr VOH Hi~pel42 and his associates, de Brittevil~e43, WI44, Ginaburg45 Jackson and Peddish46, ana Coursey and Brand470 These researches are being continued by numerous theorists and ex~eri~.er~orse Here again the ,eriter of this section is trespassing on ground rightfully belonging to the section on ceramic insulation. Cons sequen~cly,~, only brief reference will be given to the ~rariotas bakers dealing Pith Chin sub ject Pith one exception. JUG is felt that the splendid postula~Gion of Professor von Elipnel and his . . a~socia~ces concerning the correlation between dielectric be_ havior and structure deserves special consideration in this section. Wul has published a number of mpers dealing with various aspects of the dielectric behavior of the titar~tes. . . Ginsburg ~liscusses the die, ect-~ic properties of ferroelectric crystals and barium titanate. Jackson and Reddish report the results of their investigations on high permittivity crystalline aggregates. Coursey and Brand discuss their measurements on BaTi03, Ce.-TiO3, BrTiO3, and mixtures of BaTiO3 High SrTiO30 They f ound that the temperature at which the peak dielectric c onstent occurs in such mixtures decreases ~ inearly from 1 250C. for BeTiO3 to . 6C>oC. for l:l mixture. deBritte~ril7e has made an oscillogra~h study of the dielectric properties of 13aTiO30 Professor Ron Ridge] and his associates give a very com~rehen- si~re treatment of the whole sub fleck inc1 udi ng a general survey of the fi eld and their own original contributions. I4c seems go be general! y agreed among the various investigators that BaTiO3 end the 3a_Br titivate solid solutions constitute ~ new c las ~ of f erroe Technic mat eri ale O von Hin~elts namer gives particular consideration to the correlation between dielectric behavior and structure of the titanates. Tt is pointed out that the alkaline earth titan- ates may be classified into Agree groups * The flirts, represented by MgTiO3 alone, choirs the properties of a norme1 tonic crystal _ )01' 6 ', TOW 1088 9 and a positive temnere~re coefficient of di- electric constant. The fig++ and Tim+ ions are about equal in radius; c onsequent~ y ~ the Or ions share three oxygen ions as equal Anew, in equivalent ~sition.s Rheas producing a hexa- gone~ structure of predominantly ionic bond character. The funde-mental atomic arrangemer~G in the other two groups can be represented by the ~eudo-cubic 't~ero~rskite structured Each Pi ion is surrounded by six oxygens forming an octahedral ~ ]!3

grou~lng ss in TiO2 Whereas the alkaline earth ions placed at the corners of the cube are surrounded by twelve oxygen ions. It is shown that all titanates containing Riot octahedra may be expected to exhibit high dielectric constants resulting from the transition between hetero~olar arid homopolar bonds as the Ti ion is dis?~?~ced Judith respect to its oxygen surroundings. In addition, a trend from Ca to Ba may be er~ticinated because With increasing size of these spacer ions, the octahedra will be systematically distorted X-ray data shover that the structure cuff CaTiO3 persists up to at least 550°~. so that there is rto transition and cor~seauently only the high ~olarizability of the rutile type may be expected without dielectric anomalies. The situation for BrTiO, is similar. The case of Patios is considerably more complicated. ts dielectric constant of abmt 355 at -121 °C . and corres~ond- ing values at about +~00°C. indicate that a high polarization of the usual Futile type exists; superimposed on it are some other effects in the intermediate temperature range. The ~ arge neek in £ ~ iS connected with a transition in lattice structure from ~Getragonal to cubic . The fold ocarina tentative picture for the behavior of BaTiO3 is proposed: The pseudo_cubic form con- sists really of hero modifications characterized by a Permanent moment, oriented in opposite directio ns . The two equivalent energy states of the twinned modifications coalesce at the transitior~ temperature into a simple state corresponding to the nonpolar cubic structure. The diel ectric constant peak would represent ~ situation in 'which the applied field may being about transitions bets een the hero states with opposite electric moments, whereas at low temperatures the energy barrier separating the states becomes too high anile at higher t em_ Erasures the Hero states merges As the transition between the eq'`~i~ralent states becomes impossible at lower temperatures, ~ . . . decrease in £ ~ t0 the val.ae elected from the normal rutile type notarization is antici~atede Although no structural change is observed, the region of the lower maxima in £' and it eventual drop is accompanied by substantial 1 attice changes . This region of strong contraction of. the lattice may well co- in c i de tori th th e r egi on '-die r e the f i e l ~ can n o ~ o nger o~rerc ome the barrier between the 'win modifications. 'the complex nature Of the i' and tan ~ choracteristic.s for BaTiO3 shows thug the s itue.ti on is very i evolved. IT C e Di~ol e Moments and Structure ~ _ Dixon e moment measurements have in many instances been a. useful cool for determining the Ire of molecules es_ ecin11.y cord th regard to the disposition of cola' groups. The theory of poled dielectrics is considered by Bauer48 in torso goners, Part I dealing with the theory of the crystalline field in solids and liquids and Part IT, high the comparison between theory and ex~e~iment~1 xesu11~. Expressions are derived - 14 _

for the resultant dipole moment (ft) and the effect of the crys- tel~ine field on the molar polarization of orientation of the dipoles in solids and liquids. These expressions are ade~r'!ed to the Sari our field sharers thug depend on the charge distribution in the molecules. In general, satisfactory agreement wets ob_ tained between these formulae and ex',erimental results for a v~.ri ety of subetenc e ~ such as lo e, water, alumna, hat ide s of hydr o- gen end. salts of ammonia. Tt is found that the properties of the crystalline field in li quids ~ are analogous to those of solids ~t the ~elaxati on times are much shorter of the order of 10-~0 to 10-~i see e due to the brief lifetime of as sociation of a molecul e with the immedia.te neighbors. Another treatment of the theory of dipole interaction ire crystele is given by Luttinger and Tiaza49. The results of their analysis were found to be in good agreement Pith the experiments of He as and Wiersma on CsTi alum. B5ttcher50 has shown mathematically that even for aniso_ tropic dipole molecules the mean nolarizability is practically equal to (~l+~2+<X5)/3 adhere the at e are the polm~iza.biJities ire the three principle directions provided tne electric field is homogeneous and there is no saturation. In a second paper, B51tcher describes a method for calculating the polerizability of the particles of a substance from the index. of refraction end the density of dilute solutions of that substance. The stasis_ t;\ca~ treatment for determining the variation of the heat of adsorption of Molar molecules is extended by Millers) to show how the varia4ci on of the dipole moment Erich the fracti on of the surface covered can be Ogden into account. The equations have been used to determine the variation of the heat of adsorption of t~3 on a non-conducting surface. Hanney and Smyth have Published a series of four rawer discussing the results of their dipole mount investigations. The first r)pner52 is on the dinoJe moment of hydrogen [luoricle ah.. the ionic character of bonds. The moment ads measured in the error state and. is numerically identical with the el ectro_ negativity difference be~G~'reen the ~ aunt F calculated from energy dacha. ~ ~ is concluded they; the X-F bond has 43)~; ionic character. A new tal?1e of ionic bonci character ~ given. The second na~er53 deal ~ '`~i Ah further inure ~ hi get ions of pole. rity in hyc ro ce rbons ?:os~esaing con jug~cecl systems. They found that i;he measured moments of severed additional compounds are c insistent ''ritl~^ the mod ecus or st~rUct:ures required by the theory of hy~ercon.jugation and resonance discussed in ~ Previous ~a.r~er and thus lende sunr~ort to this the ory e Dinole moment and resonance in viny' sulfide and six unsaturated.. chlorohydrocarbons is the subject of the third r~aner54. ERG lops found the t the double bonds remote from the Cl in Ache oro_ 1,2_butadlene and ally chloride cause only small. lo.,erings of the Zircon e mo~;ents but the addend effect of the methyl group in methe lL_ ly! chlorite gives ~ propylene _ like dipole moment in the h,y~ro- carbon chain and increases the ~ offering of the dipole moment

below t.het of the corresponding satu-~.ted molecule. The three chlorocrocylene molecules here dipole moments the t conform closely go the r~a,~irements of Their k.nol~rn geome~riGe] configurations, the dinol e moments associated smith component ~arts, end the effects of resonance. In these molecules, as in many others, the effects of resonance lend thern.~e1'res to vector addition along with the group moments whi ch they effect, alto Hugh there may be Unusual influence of resonance effects with consequent alteration in moment. The dipole moment of vinyl s~.Ifiae gives evidence of owering by resonance like that in vinyl chat oride. In the fourth ~a~er55, handy and Srnyth discuss the divot e moments and structures of ketene and of several molar notes containing con.Jugated systems. The 7c,~`r~ of ketene is consistent with the recut ~Gs of electron diffraction and ~ n- dica.tes some ansiogy between its structure and that of CO. The oxygen has much less negative charge then the ordinary cerbony~ oxygen. The dipole moments of the four mol ecules ,`!~th conjugated systems give e~ricence cuff resonating structures and consequent o~ari4cie~. ene~ogous to those previously observed in their ]~.bore- t cry . Rogers and Young56 reported on the electric moment of n butyllithium and the nature of the Li_C bond. Taking the molar Doe erization of n-butyIlithium in benzene at infinite dilution e-s 40, and estimating a Prague of l.0 for the atomic fraction of Li, the authors ce`Icul?.te a ~ - 0.97D for the dipole moment of n-buty, ~ ithium, thus indicating; that the Li_C bond must have consid.er~.ble comer ent character since ion pairs would recult in very much higher ~re.]ues of the molar dot arization. From the electronega~civity difference, 1.5 units, between C and Li, one would ~red' ct about 45< ionic character for the Li-C bond and a bond moment of about l.5D. The observed bond moment ~ s le37D assuming the C-R bond moment to be 0.4D and taking Li as the flus end calf +,he dipole. Lithium alkyl s may thus be re- g~sraea as covalent compounds, the rather large amount of ionic character of the Li_C bond being about equal in magnitude to the ~c of the C_F bond. atorni c Sauer and Mead57 hare determined the dielectric con- stants at 20oC. ana 60 cycles/sec. for a series of linear holy_ me~chyl~olysiloxanes: (CF333Si ~Si(CH3 )2] qC~3 in which q has the values 1, 2, 3, 4 and 5, and for a series of cyclic polymethyl colysiloxanes: g(CE3 )aSiO]q in which q has the values 4, 5, 6, 7 and 8. The dipole moments of these compounds were computed using Onsager' ~ eaua~Gion. The moments of the linear compounds Deere founc' to agree satisfe.ctorily smith the simple empirical relation: ~ = 0.70 by. For the cyclic compounds, the moments of the larger rings appear to approach the values predicted by the ~ equation. The Si_O_Si bond angel e Ares calcul ated from the of hexernethyl disiloxane (0.74D) and appears to be 160 ~ 15° The dipole moment of ~ -nitrobutane ~ n benzene solution - 16

at 25°C. hes been measured by Miller and Angel58. The value ob_ tained is 71 = 3.40 + 0.01D. A review of previously reported measurements on the higher nitro~=affins suggests that 3.4D is a correct figure for the solution Prague of the nitro-group moment in these compounds. According to Gent59, the molecular electric moments for nonmesomeric molecu] es is divided into the vector sums of the group moments and of the induced moments. In model 1, the induced ~ is calculated separately for every atom in the molecule. Equations relating molecular~, group moments and induced moments give `~(CH2_0) = 2.05D and ,*~-C) = _0.46D. In model 2, i'G is aB- sumed that the bonding electron pair between two atoms is concen- trated et the point of contact of spheres of the appropriate co- ve.lent radii. For this model, p(CHz-O) = 1.83D end ~(H-C) = -0.41D the ~re..lues for '`(CH~)~:O and ~(CH;~)3:0 lie between the two calculated rally: ~(CH2)4:0 id close to that for model 2; theme O Me) is remold from the ca-1cule-~ce values. Ste~oanenko and Agranat60 have determined the dipole moments of pal~nitic acid and triT)almi~rin in benzene, cyclohexane and dioxane soluti one . Ster~anenko and Noviko~ra.6) hare measured the Selectric constants and absorption coefficients of stearic, oleic ~d linoleic acids and of tristearin and triolein at a serape_ 1 ength of 3.44 meters and at temperatures frown ~60 to 100°C . Various proposed formulae severe tried for red ating the results to the dipole moments of the same compounds measured in solution, but all failed, presumably because of molect~ar association. Data are liven by Sninrad62 for the dielectric constant, molar polarization, molar refraction and dipole moment of chlor benzene, monochIorocyc] onronane, and I, 2-dichiorocyclo~ropane as measured in benzene solution with a Schering-bridge. The moment of I,2-dichloroc`Yc~opropane indicates that this molecule must here the dt _configu~ation. mbe angle of the C-C! bond ,,'!ith the ring plane appears to be 48° which would make the exterior angle of cycle onronane 96°. Rogers and Robertson give data for the di- electric constant, density and co]arization in benzene at 25°C., and for the molar refraction, polarization and dipole moment of a number of cyclo~ro7?ane derivatives. The moments of cycle_ rocy~chlo~ide and I, 1_clichloroc,ycl opropane in benzene solution are about 0.30 Begs thmn the corresponding cyclopenty~ coonhounds. This behavior is in4Ger~-eted as indicating a small contribution . .. from ionic resonance structures analogous to the principal tonic res onance st~llcture.s in vinyl chl office and chl orobenzene. The mo~..en.-s of the cyclor~enty! halides and cyand de are close to those o~ the corresponding secondary aliphe.tic compounds. II D. Plgh Voltage Phenomena The Parsons Memorial Lecture delivered by Da~ris64 before Ah e I n s ti Put e of El e c t r i c al anti n e er s ~ Loncl. o n ) rTo~rember, 1945, gave an account of the methods for producing and mea.suring high To rer e..c . ~ d.c., and surge vo]tage.s. Two problems towards the solution of which high voltage research has made a contribution _ 17 -

e.re considered. The first is concerned '^rith the insulation of high Rotate t-ar3~mi`ssion lines and the disposition of such in- su~ Cation so as to insure that ine~rite.ble breakdowns are confined GO the more readily renewed carts of the system. The second problem is a Alar time an~1ice.tion concerned with the prot.ec4cion of teal loons Band crepe from hazards due to lightning. A rather long summery dealing Faith the influence of irrn.diati,on on the measurement of impulse Frontages with anhere gets is given by Meek65. Posin66 has investigated the lowering Of electrical breekdo',rn field strength at microspore frequencies due to an exterr~1 ly earlier m~gne~cic field. The following effects liege obeer~red in connect; ton with 3 cm. microwa~re brea.'x_ corn studies conducted on eir gaps in Rave guides: 1. An encroach. of ~ ~ermcQ-nent magnet to a gad which is on the verge of create sparking can make the gap scarkover. 2. A reigned of pole_fe.ce cross section smaller than the Hatch of ''rove guide over which it is passed may lower the break_ ~ In field strength by 204~ or more depending on certain con- ditions such as the strength of the magnetic fiel ~ and height of the breakdown gap. Be then a magnet is street along on the outside of the ve~tically_narrowed t.~a~reguide, the gar, may spark at a field strength lo-,~rer try as much as a factor of 2 or more than when the magnet is a-been-. 4. No sparking effect can be reliably reported when the nagnetic field is applied at right angles to the micro are electric Vector, either along the direction of propagation or crosswise to it. 5. Wher1 broad face permanent magnets are used, the poised effect and the s'`reen effect are very much diminished. tlarious possible explanations of these phenomena are c ons idered but none ~ eems at the moment to be adequate . In ~ letter to the editor, Thonemann67 reports the results of his experiments Perish high-freauency discharge as an ion source. Diel ectric recovery by an a.c. arc in air blast is di s cue s e d by Br of . The permanent r~hysicochemical changes resu: tiny from d.lech~rges in hydrogen were investigated by tTikuradse and Berger69 f or rare of ~ , 11 n s e ed of ~ a, Of f in of l ~ olelc ac id and ~ t earl c acid in a special a.p~aratus ~ The increase in ~ ' and in dielectric .. .. ~ol~ization :~s found to be proportional to the increase in vis .~ comity _ Molar substances showing the greater change. The dipole moment of oleic acid eras observed to change from 0.7~ to 1.08D iffier ~ hours treatment. _ 18 -

Various high trot tage investigations on miscellaneous solids have been reported. Seeger70 has given a discussion of electric breakdown in solids. Adamant has studied certain factors influencing the dielectric strength of paper such as gas Are. cure, moisture content, temperature, sheet density and sheet th$c~ese. The method and apparatus used in the expert_ meets are de scribed and the results are discussed. Rutol.o and Graves72 present data for the breakcrown stre ~gth of 17 samplers of straight-cut varnished cambrics and lo samples of bias_cut varnished combine The samples in- cluded 4 thicknesses of by ack varnished cambric cloth, both bias ma strai~ht_cut, representing 5 manufacturers and several se.m~?len of yellow varnished cambric. The effects of humidity, electrodes and breakdown media were studied. Thee electrode assemblies were used: (~) 1/4~ ala. circular, (2) 2" dia. cir- cular, e.nd (3) l/4~ ~ 4" rectangular. The test equipment and procedure are described. Dielectric strength after moisture conditioning (96¢ R.SI.) in general Auras found to be about 75% Coverer than the dry Prague (clo~c R... This-difference varied with thickness, ~nois~cure .sho:~,ing 1 ess effect on the thicker samples. hen considering 12 mid black materials only, it was noted that the bias-cut shorted a greater moisture effect than the straight_cut. Considerable difference in the effect of hum' city alas found for samples from various manufacturers. Using the 2" ciroul ar electrodes as a reference base, ap~roxi_ mately 590 higher dielectric strengths and about 27jo higher values there obtained smith the l/~" x 4't rec~Gan~lar and 1/~" dia. circular electrodes respectively. These variations there . more accentuated on the bias_cut than on the strai£ht-cut me.&Gerials. Dielectric breakdown in air ached to be abo':t 9,< lower than that in oil . In genes, the average dielectric breakdown strength of oias_cut cloths was about 25% lower than Ache ~ f or ~ tori ~ht-cut Gnat Erich .n . Aueten and Pelzer have measured the dielectric strength of paraffins end some high polymers for comparison theories of electronic breaks and also on account of the bearing on industrial applications of dielectrics. Attempts to measure the dielectric strength of paraffins severe unsuccessful, except for material oriented by pressing, because of the poor mechanical properties of such substances. Satiefactor~r tests were made on noly~hene, which gave a Prague of ably 6.5 x 10 volts/cm. frown room temperature to -190°C. and on polyvinyl chloride-acetate, the dielectric strength of which increased from about 6.5 x 10 volte/cm. at room tem~era~Gu~e to 12 a lo6 room. at -190°C. The nolythene eras crystalline end the results correspond to those for inorganic crys~ca.~line me4Gerials and with the theory for such crystal ~ . The conol yawner was amok_ Shout, its behavior being similar to the t of varnishes and may be explained by Fr~hlich's snort recent development of the theory for amorphous substances. The effect of tem~era~Gu~e upon the ore entation of

electrica ~ breakdown Lathe in the alkali halide cryostats has been investigated by Davis son74. The results obtained suggest the existence of a path sequence: random - -- ~ (loO) r (1 ll) - -A (~10) Waxy) assumed by the direction of breakdown as the 1 Entice energy or temperature ~ ncreases. Ster ~at!,erns of 12 non-primitive lattice directions were observed in Li C] and Li F. Mixed and imbue crystal ~ grown from the melt tena to exhibit high temperature bash ~&Gterns at low temperatures. By extending the study at room temperature to crystals possessing difference bonding and symmetry Properties, general laws governing path orientation are established. Tt is shown that the Toshiba e path directions de- ~end upon the macroscopic symmetry prevailing and are a~paren~Gly not influenced by the type of lattice bond. The author concludes that before crsnsid.ering ~ meche.nis~n for breakdown path orientation, one should be temilier moth ret ated electronic phenomena in crys- tals. A revie:~.r of pertinent information Bras presented by Professor von lithe at the Conference on Dielectrics et Bristol in 1946. von Hillel discusses the problem of breakdown math . . ori~ente!4 on in the frame of his general theory on the breakdown o' solid ale7ectrice. The mechanism which he has evolved is based on the assumption that the paths mark directions for which there is least transfer of energy from excess electrons, Rich are accelerated by the applied fielcl., to the lattice. The path directions are believed to depend upon the wavelength and hence upon the velocity of excess electrons . The orienting mechanism Proposed by him ts electron ''acre interaction with the lattice . that results in sca.Gtering into preferential lice directions. A retried of surface discharge phenomena on bushing in- sulators is given by Wright75. It is nolnted out that a general solution for the electrical characteristi cs of bushing insulators is not at Present possible because of the complex laws of elec_ lyrical breaRc~o,~rn and discharge phenomena of dielectrics and the nathemat;ical diff~icu~ ties of solving the La~lace equation for a 3-dirnensiona' electric field having the boundary conditions met with for practical bushings. Several methods have been proposed to obtain some general principles of design but only that dealing enrich the Caleb] ation of the surface discharge voltage and anark- o~rer voltage based on the laws of the gliding discharge and the concert of. surface capacitance are dealt Erich in this papers IT E. Microwaves We now come to the subject of micro~'rav~es which are al_ ready Playing an important rol e in s~tlOying the carrel ation be- t~?een dielectric Properties and structure. A better under- standing of the fundamental concerts of microwaves and the analysts and rapid de~re70~ment of microwave components and equi~- ment as ~ result of the last war have overfed up new horizons for _ 20

dielectric exploration. All microwave research and development work during the Terror was classified material and hence was not generally availehie. Now the t these restrictions have in many instances been removed, the literature is flooded :'rith articles dealing with the various aspects Or microwave Necrology. In hew of the newness of this field, and the present and future interest in dielectric investigations at microwave freauencles, it ',Tas decided to corer the literature rather ex_ tens ively in this retried. The ~ ecus ai on of microwaves will accordingly be divided into three Subgroups: the fires dealing Erich the fundamental sconce,;, the second, Keith the analysis of nQicrowa~re coa'nonenta and the third, with microstate resonance ~ no abs orr'1i on Phenomena. . . , IT Eels Fundamental Concerts of Micro,~avea As previously indicated, the literature on microwaves f or 1946 is i refeed ~rolumir~ous. In order to keep this review a reasonable length, it is necessary to limit the number of refer_ ences cited and to merely indicate in most instances the nature of the sub Sect matter treated. The artic les range ~ n scope from very general articles written for popular consumption to very detailed mathematical anaigsia of specif ic croble ~ . Hil176 has written a very interesting popular and pictorial articl e showing the smooth conti nudity of the changes that prewrap ~ as one proceeds up the en ectromagnetic frequency .. ~ spectrum from d-c up to cm. waves and higher. Maxtrell's electro_ magnetic field theory is shown to be completely adequate to ex_ In the whole range of electrical phenomena from a_c to say 10 cycles/sec. Generators and detectors of higher frequencies consist of atomic arid molecular systems and many of the phenomena require the quantum theory for their descri rtion. Power ~d audio_commun'cation frequencies circuit elements of inductance, capacitance and resistance and working Erich current and voltage measurements. This procedure essentially eliminates the necessity of considering the electric ena magnetic fields in the description of the electrical phenomena involved.. This so-called t'1um~ed circuit" treatment can be en_ tended gel into the radio-frecuency region if proper precautions are takenO Unhewn dealing filth the microbe region, ho,.^rever, these methods are of little use. The electric and magnetic fields are now of prime importance. Instead of resonant circuits consisting of A, C, and R. resonant caviJGies operating in specific modes or field configurations are encountered. Tra.ns- mission lines become hollow Flies, not parallel ''rtres or twisted hairs. Their very name _ waveguides _ emphasizes that their prime function is to contain and hide the electric and magnetic fields that constitute these 'guided ~`raves". The anant,it]es measured are like~r.'ise different. At loser frequencies, currents, rouge, inductance, ca~aci~Gance, resistance and fre- quency measurements are of prime importance; in micro~.ra~re measure_ Detente, Moorer attenuation, wavelength, standing wave ratio and position are the Quantities ~ought. are adequa~cel.Y treated by defining - 21 _

A ~3P.~er77 by Andrew on microwave optics is concerned weigh the study of micron in free space and the performance both micro' cares of the experiments commonly discussed in text_ books and 1 at?or~.tory Unequals in physical optics . The essential units designed for the study of microwave optics are a trans- mitter for reduction of the radiation and an intensity meter with~which to explore the field of radiation. The Construction end operation of these hand-sized units are described. The . . transmitter has a coffer output of a few hundred rrilllwatts and one at a '~.'rel ength of about 1 2.5 cm. Some of the ennui_ meets that can be performed Parish this equipment are indicated. Slater78 has written a splendid 71 page review article or micro are electronics . By microwave el ectronics g Slater refers to the study of electromagnetic fields in regions of the order of ~ crave ength in dimensions, bounded by reflecting Irk] ~ 8., arid of the int;er~c~Gion of these fields with electrons, ions, or other forms of space charge . It includes the hole high frequency side of micro~,Ta~re radar; the nature of wave guides alla resonant cavities; and the rapture of electronic tubes such es klystrons and magnetrons in which transit time is of fundamental importance. Tt also includes such devices as cyclo- tron~q' synchrotrons,, linear accelerators, and other Reprices for the acceleration of charged Articles* During the I! there was a very great development in the knowledge of microwaves. The study of wave guides and resonant cavities, originated be_ fore the ever, loran carried to a point of great advancement. The klystron developed before the war became much better known and highly perfected. The magnetron oscillator Arty improved to the Aunt where it pros a generator of mlcro';rave power of very great ca~a~bilities . All of these developments, particularly as they ,~rere carried on at the MIT Radiation Laboratory drill be dis_ cussed at length in the series of books to be issued from that leboretory and published by the ~c~ra~r-Hill Book Company. Other versions of the same information halve beer, or will be, contained in publications from industrial laboratories in various ~eriodi_ calm Even these articles, extensive as they '.~1 be, represent but a small fraction of the great literature Which exists in the form of cle-~sified, or farmer' y classified reports prepared during the war. Slater has tried to introduce into this fief ~ a corre- lotion and unity 'which are perhaps ~ acking in most of the other work . The sub] ect matter is treated in five chapters: I, the four-terminal network and the t~ansm.is~ on line; IT, wave guides; TIT g resonance cavities; T1r, anplicatior~s of the theory of re ~ Boning cavities and Ire electronics of the reflex klystron and magnetron. The first chapter deals with (13 the definition of the four-term~nal network and the transmission line, (2) the exponential solution for voltage and currents (33 the terminated line, (4) the impedance of the terminated line,, (5 ) bilinear transformations, (6) graphical discussion of bilinear trance formation, (7) special types of networks and lines, (~) trans- ~ormation of residuary and reactance coordinates, (9) the 22

continuous transmission line, (10) standing wave ratios, (11) transformers between transmission lines, (12) determination of transformer constants, (13) a loasless transformer as a shunt or series reactance, (14) Dower flow in netw~or3~e and bans_ mission knee, (15) power flow from a lossless line into a ter- mine~l impedance, (16) circuit efficiency and insertion loss of a resistive network and (17) a resume of network theory. Chanter TI deals Erich ~ l) the electromagnetic field in a wave guide 9 (2) transverse electric and transverse magnetic modes, (3) standing waves and reflection coefficients, (4) impedance and Tourer flow, (5) expansion of the field in normal modes and (6) \08SeS in the wave Mae. In Chapter TIT, Slater discusses (~) orthogonal functions for a hollow cavity, (2) Maxwe11ts equations for a hollower cavity, (3) free and damped oscillations of a re_ sonant cavity, (4) the unloaded Q. (5) the incus impedance of a clarity, (6) currents within the cavity and (7) perturbation of boundaries. Chanter IV treats (1) the tuning of resonant cavities, ~ 2) measurement of the properties of a cavity resonator, (3) Coffer flow through ~ cavity, (4) ~ropertles of ~ nelf_excited oscillator ~ (5 ~ out nut of an oscillator as a function of load (6) starting of an oscillator and (7) ex:>eri~nental investigation of electronic admittance. The final chapter deals with (l) the reflex klystron, (2) the electronic operation of the reflex klys tron S ~ ~ ~ power and frequency of re f lex klystrons , ~ ~ ~ the magnetron, (5) the resonant circuit of the magnetron, (6) elec_ tron motions in the magnetron and (7) opera.ting^r~racteristic~ of the magnetron. The relation between nodal Positions and standing wave ratio in a composite transn~1ssion system is discussed by Feenberg79 Reflection generally occurs at a lossless transition region Join- ing To uniform transmission lines. If the output line feeds into a matched load (no reflections, a sang '`rave ratio,~o, different from unity exists on the input side of the transition region. If the output line is terminated by a ~raria.ble position short,, a relation exi sts between the nodal Positions on opposite sides of the transttion region. This relation can be used to dete~ine 40 thus dispensing with the need for a calibrated de_ tecting system to measure this quantity. For the purpose or this paper, a composite transmission line is defined to be one composed of into uniform ~oss~ess sections (coaxial or cadre guide) Joined by any sort of lossless adapter. In pe rticu:Lar, the system may be simply ~ single uniform line containing a Ios sless irregularity (window' supporting bead, gab section, etc.; Size somewhere along the line. Systems of this general type are employecl in many veri etie s of microwave equipment and me ;~.surement apparatus . Actual systems are not lossTess bare it is gene-~ly true that poker losses are kept to a minimum by good design. vilest has gi Wren a rigorous discussion of impedance concerts in Claire guides and has appalled them to the analysis Of a plane discontinuity in the form of a Junction between two guides of arbi trary cross -sections se?:ar~ted by an infinitely - 23 -

thin diaphragm having arbitrary openings. The general equivalent circuit is represented by ~ ~ network but it is chosen that there is one important category of problems where this T section reduces to art Intel. transformer flus ~ shunt element which in turn may be reduced to a~ afire shunt element. The formulation of a Or network is also discussed. The theory is applied to ~ transverse Curare, ca~citative and inductive Ins, arid ca,:acitative and inductive changes of cross~secti on in a rectangul or where guide, and ap~roxi- mate expressions for their impedances are deduced. A rather ex_ tensive treat~.ent of the ca?~.citative window is given in order to demonstrate the Potentiality es of the method. The feasibi lily of dielectric crave guides is discussed in Electronics8~. Solid dielectric wave guides might be used at the upper limits of the sunerhigh frequency range. Hoverer, some of the transmitted energy is carried outside of the dielectric Prove guide unless the guide is made large enough or of ~ material having ~o high ~ died ectric constant that very many modes are nron~gated. If such ~ guide were used 9 there aground be the as yet unsoured problem of coupling in such a manner as to match to these many higher Bodes. An Stick e by Travison~~ sets forth the basic conceives of the transmission of electric and magnetic cadres through a Claire guide. Until ~ fell years ago, serape guides were a type of trans- mission 1 ine having considerable theoretical interest but ~ ittle Practical unit ity. The basic physical ~rinctn~ es governing their operation ~`rere dearer owed and published before the war but wide_ spread use during the last few years has reduced their seemingly complex behavior tc' a set rid engineering principles ~ Prac Vicar con.sidera~cione in the choice and fabrication of cadre guides are treated by Morenot33 from the engineering standpoint. The advan- sages of ho] ].o1Y, rectangular guides are described by co~nparison with coaxial cable characteristics at su~er-high frequencies. The fo1lo,dng thrice are discussed: choices of conductor, low attenuatior1 in guides, high ocher capacity, disadvantages of limited bandwidth, dimensions vet applications, standard sizes in use, Mare guide materials, metal finishes, nlating techniques, losses in related surfaces, velocities in cadre guides, power limi- ~ca~Gions and breakdown at high a.:~titudes. A microwave spectrum covering the range 2100 to 30,000 mc. shoaling the F.C.Ce allo_ co.ti ons and the standard wave guide dimensi one suitable for use at various frequencies is i~ ~ ustrated. A condensed review of basic principles and some of the lo artime developed techniques which make the field of ultra_high frequency fertile ground for many never developments in Peacetime is given by Seely84. In a second Leper, Seely discusses the fund~m~entn~ che.racterist] Cal of USE transmission lines with alkali_ cations in UHF equipment used in radar, television and other c ommuni c anti on ~ ye tems O ~ 24

Glinski85 shoals hoer by the a~plica.tion of the standard transmission line the ory9 the standing Grave method of measuring impedance can be extender} to the case of trana~niesion lines with ?~ckenuation if the e.~ronriate corrections are introduced. The - er brings together and acmek~at systematizes information avail able in the existing technical literatil~e. The condition for minimum atf:entuation in Grave guides is treated by Phillins8 . A short mathematical article by Walker ana \`raX87 gives a first order differential equation for the volt_ age reflection coed cient of a non-unif orm line and it is shown how this equation may be used go calculate the resonant Berate_ lengths of. tapered lines Attenuation and Q factors in wave guides are discussed by Clavier§8. Eem439elucidates the nuzzling pheno- menon of decreasing attenuation with increasing frequency which occurs in a few isolated instances, by treating the guides con- cerned as limiting cases of a "aide of snore general share in the interior of Rich the waves display the normal properties charac- teristic of ret in guides generality. The equations of the elect~c>_magnetic field, cut-off frequencies ~d attentuation des- cr'bing the isolated cases are then, in like manner, deduced as limiting caSes from Choose appropriate to a guide of General shape. he ~erturba4Gion theory of the normal anodes for an ex . . exponential M-cur~re in non-ster~dard propagation of ~nicrowa~res is expounded by Pekeria90. Electron ballistics in high frequency fields is the subject of a 30 cage article by Sa.muel9~. Clarke92 presents some novel expires si one for the propagation constant of a uniform line in enrich the attenuation constant its expressed in te~s of the !nost fundamental entity known, nP-~me~y energy, and the characteristic impedance is stated in therms of the chase velocity. A discussion of the present status of the microwave art nertic,~larly as it applies to radio detection and ranging is riven by Whited. Ford exit Oli~rer94 report the results of their experimental investigation of the refl ection and absorption of radiation of 9 cm. wave_length. Millimeter wave propagation is discussed by Lamont and Watson95 and also by Mueller96. Robertson and K'r~g97 have investigated the effect of rain upon the ~ropa`- ga~Gion of bares in the 1_ and 3-cm. regions. The Doppler effect in ~ waste guide has been examined by Ma1.ov98. Roz ovsky99 here considered the propagation of the electro_me gnetic fief ~ in dielectrics with a dielectric afteraction and in conductors Irish magnetic af~ceraction. Thone~ann ad King)°° have observed that the inner conductor of ~ coaxial line which is tuned to frequencies near 1000 mc. and which projects into an arc dis- char~e in mercury orator can be excited by the discharge if a bar garnet is brought near the tube. Kelliher and b~raltonlOl have studied the Production of mic~o-electromagnetic Graves by .s}'ar king technique ~ . The 7 it;er&+ure on the principles of ope-~tion, construction - 25 _

and application of Sari ~s com~onen~Gs for microwave systems is so extensive that little more than ~ bibliography can be given in this review. A wave guide system may contain a considerable number of ''eve gamine sections and components such as microwave oscil ~ Store , straight; sections,, bends, Egoists, right angle corners, rotating Joints ~ ca~acitati~re or inductive windows, coaxial to wave guide affecters, adapters from one size guide to another, Are meters, a resonant cavity, standing wave indicators, direc- tiona~ couplers, "magic teest', variable and fixed attenuations, dummy loads or terminations, flexible wave guide sections, trans- formers and crystal converters or rectifiers. Since it is ger~era.1ly desirable to be able to interchange components they must be assembled High suitable connectors. Al 1 these com- nonents must be carefully engineered and fabricated to avoid undue ~ oases or undesirable ref] actions . A general discuselon of Caere guide connectors, wave guide bends, wave guide thyme, wave guide corners, tee Joints in wave guides, matching dis~hragms arid Boats and coaxial line to wave guide transformers is given by Morenot02. The appli_ cation of mic& Norms as elements in ~nicro~rave systems is dis- cussed by Master and 0a associates, and Fiske 04 describes the use of resonant Rancor for vacuum seals in rectangular Brave guides. The theory and exoerimental behavior of right any] ed Junctions in rectangular ware guides is considered by Allansonl05 and hire coworkers. La~b)°~ has determined the experimental be- havior of the coaxial line stub. Flexible wave guides are des- cribed by Winchell '07, an] by Anderson and Winchel1~3. The tonics; included in Hill' ~ O paper are: the stability of mag- netrons, C.W. oscillators, micro~va~re transmission lines, coaxial lines, ''ave guides, impedance measuremen1;s on transmission lines, moving Joints, duplexing, detection of microwaves, crystal mixers, and crystal impedances. A detailed account of the development of silicon crystal rectifiers for microwave radar receivers is presented by Scaff and OhlliO. Hassel and Jenks 1 describe the rincinies of electroforming techniques for the fabrication of high precision wave guides and other parts for microwave apparatus. The heart of any micro'''ave system is of course the source of dower or the oncil lator. Some idea of the intense research and develoumen~G Whorl: on microwave oscillators carried on during the Bran can be obtained by referring to the excellent Sl page disserta~Gion on the magnetron as a generator of cm. waves ~ub- fished by Fisk, Rage trum and Hartman and by the wealth of literature on this subject. In Part ~ of their paper, Fisk and his collaborators review the present knowledge and the fundamen- te.~s of the theory of the magnetron oscillator, bringing together in one place the results of work done by all the magnetron re_ search groups. The topics conquered include: (~) a general discussion of the magnetron oscillator, (2) types of magnetron oscillators, (3) the electronic mechanism, (4) conditions re- lating measureabJe parameters, (5) the r.f. circuit of. the mag- netron oscillator, (6) resonator systems, (7) separation of mode frequencies (~) output circuit and load, (9) equivalent circuit theory arid t1Q) special topics. Part IT traces the research and - 26

development work done at the Bel1 Telephone Laboratories on the magnetron oscillator during the war ye are; fifteen different types or tami, les cuff magnetrons were developed. Work has been done throughout the range at wave-lengths from *5 cm. to ~ cm. alla on magnetrons capable of developing over one megawatt peak r . f. power. This program has included Ok on such {eatl;~res as 'tuning, coaxial and wave guide outputs, several types of resonator systems and stra~nlug schemes, and on the lncor~oration of the magnetic circuit into the magnetron structure in so-called ''packaged" tynea. . . 8later's78 review already referred to likewise contains an excellent discuselon of magnetism. papers on the cavity mag- netror~ were published by Flanders , by Randallll4, and by Johnson~l5 Coltmanll6 discusses resonant cavity magnetrons, and Le.tha~nil7 and his associates give an introduction to multi_ resonator magnetrons The Magnetron and Klystron is the sub feet of a Barer by Wall' '8, and the Mult~reflection Tube _ ~ New Osclllator for very Short <raves 1e the title of a paper by Coeterieril9 . The factors which affect the frequency limitation of reflex oscillators are discussed by Lafferty]2C' in a paper en_ titled Kl1limeter wave Reflex Oscillator. General design con- aiaeratione are given for the construction of oscillators of the shortest possible wave_lengtha; the highest frequency obtained being 72,000 me. Lafferty expresses doubt that oscillations of wavelengths appreciably shorter than 4 mm. can be obtained by the velocity ~nodula~Gion reflex principle 7'rith the present type of cathode and electron gun. The power output obtained from several tubes constructed with wave guide outputs ranged from 0.2 milli- watts (A - 4Ol5 mm.) to 12.7 milllwatt~ (> = 5.S c.. This poller output is regarded as ample for die~ec;~;ric measureinent and absorption studies on gases. By making one side of the resonant cavity flexible, it should be ~oe~ible to construct tubes which may be continuously tuned over a 10 to 15% wave_]ength range. Fores and Braudel2l have analyzed the moti on of electrons in an inhomogeneous electric and a homogeneous magnetic field and have demonetrated the possibility of periodic motion of electrons corresponding to harmonic vibrations. Tt is suggested to use such movements of electrons for the generation of sunerfrequenciee. Two circuits for use to con~Grol~the frequency of a micro- '~rave Qsc,,1lator by an external. high Q cavity are described by Pounding in a na,ner entitled. Electronic Frequency Stabilization of Micro''ave Oscillators ~ One of the circuits us es a microwave eculva~ent of the frequency discriminator in conjunction Keith a d.c. amr'1ifier. The other uses the cavity in a special circuit that ~ro~rides an intermediate frequency signal that is ~ m.eaeure of the difference bet'''een the frequencies of the osci.] Rancor and the cavity. The resulting stability of the occult atore is such that audible beat freauencles clan be produced between two _ it,, ~

once Restore at 10,000 me. A technique by which the frequency_ stebi]~.at' on systems described could be used to investigate, with high res olution, the structure of microwave abs oration sr~ec~Gra is discussed. Some of the other Capers dealing 'with high frequency ouch Galore are: High moorer tubes for V_~_F operation _ Salisbury:23 The reenatron _ Saliabury)24 Development of pulse triodes and circuit to give one megawatt at 60G me. - Law and others 5 Wide tuning range microwave oscillator tube Clark and Samuell26 Cavity oscil lator circuits - Gurewitsch)27 Osci~ ~ ators and amplifiers at ~ OGO me . using light- house tubes and cavity resonators in the UHF region Randy 4~3 . A description of a pride band microwave amplifier tube is given in an article in Electronicsl28 and also in an article by Kom~fnerl29 ~ Design or space considerations frequently make it diffi culture incorporate a vacuum transformer into Brave guide- output magnetrons. Malter and Molll30 indicate hose the use of quartz transformere may simplify the constructional problems. In tests at 1.25 cm., substantially identical results were obtained in tubes with quartz transformers as with those incorporating vecuum_filled transformers. A cavity res onator or resonant cavity such as employed at microstate frealuencies is a special f orm of linear circuit Rich has Pronounced advantages at extreme! y high frequencies being superior to other f orms of microt`~ve tuned circus ts . It is the frequency determini ng element in oscillators, amplifiers and detector circuits and often is employed for frequency checking in a manner similar to the lower frequency use of, absorption ,~avemetera. At cm. ~rave-lengths, the cavity resonator is the Only practical form of tuned circuit. A general discussion of various types of cavity resonators, of resonant frequency and modes, of coupling methods and of tuned cavities is published in Aerovox33~. Numerous theoretical investigations c'{ various types of resonant cavities have been made. Mo~zi32 has undertaken the calculati on of the electromagnetic fields, frequency and circuit - 28

parameters of high_frequency resonator charities. A mathematical anaigsis in which the resonant frequency of the nosed-in type of cavity is studied as a function of the cavity dimensions ts Siren: by Mayerl33, while Ludil34 is concerned with the natural fre- quencies of the E-type of a cylindrical capacitive cavity. Lindern and deVriesl35 consider the problem of flat cavities as electrical resonators and Micolasl36 presents a mathematical analysis dealing with the characteristic oscillations of solia conductors and el ectromagnetic cavities. Rezoned Cavities is the subject of a opener by ~iacolettol37 and Tunable Microwave Cavity Resonators ta the title of ~uarrera's138 paper. A very comprehensive article dealing with high Q resonant cavities for microwave testing has been published by Wil-eon,-39 and his collaborators. Formulas and charts are given which aid the design of right circular cylindrical cavity resonators operating in the TEoln mode Rich yields the highest Q for ~ given volume. :~he apnlicati on of these to the design of an echo box radar teat set is shown and Practical considerations arising in the con- struction of a tunable cavity are discussed. Another comprehen_ sive article dealing filth the met'~'ods and devices for testing microwave radars in the r.f. range from about -SOO mc. to 25,000 me. and at associated video frequencies ~s been published by Green, Fisher and Fergusoni40. Tt is pointed out that in general the cede instruments and techniques are applicable also for other microstate testing. A mathematical treatment of the coupling of cavity resonators through small orifices is given by Brodekil4l. Harrtesl42 has studied the ef.-=ect of size and placement of apertures and slots in '<alla of resonators upon loading, internal field distortion and efficiency of energy transfer from cavity to 1 oad. Ex?erimen~Ga results indicate the effect of o~eni~y; size for wanted and un- wanted radiation. A good wavemeter is an important requisite for most n'.icro:~'re measurements. Various types of we're meters covering vari cue Anti one of the frequency spectrum are described in the Ji~Gerature. A cut scussion of Awes ~d applications of microwave frequency meters is given by Jones343. A wave meter for the fre_ fluency range 155 to 255 mc. is described bar Banner)440 A yes_ cri~tion of a circular and of a rectangular type resonant cavity wavemeter for frequency measurements in the microwave region is given by McQuayl45, Rile Peakel46 deals faith cylindrical-ca~rity ,~a~remeter design. Essenl47 gives a descri~cion of four simply constructed cavity resonat;or wa~remeters covering the frecuei,cy ranges lO,f)00~4~000 me., 5,600_2,,000 me., 2700-1000 mce and 000_200 mc. The use of transmission lines as transformers is c on- side red by Bardi49 and by Quailed L50. QuariesI51 1ike~ise deals Irish tranemisei on knee as resonant circuits. Crosby arid Penny~act~er352 have mule a theoretical study c.f radio_frequency -29 ~

re ~ i store as uniform trenemi ~ si on line ~ . The increasing use of decimeter and centimeter ware_ lengths has necessitated some changes in techniques for measuring cowers The application of the bolometer method to the measurement of small r.f. Coverers is described by Hickinl55. In this method, the Tower is dissipated in a resistance having a large temperature coefficient which forts one arm of a Wheatstone bridge. By direct current Bower sub~Gution the indicator may be calibrated and the one measurement of resistance bill give the power in the load. Some Beta ils are given of indicators and circuits to deal with roosters from a feT* microwatt to a few watts at frequenci es up to 10,000 mc. The limitations of the method and possible sources of error are considered. Earlyl54 has described a wide_band direct_re2.ding wattmeter for wave guide. It uses a directional coupler and one or more thermocouples to monitor the poster trans- mitted by a cadre guide or a coaxial transmission line. It was used in connection with a 1000 '.~t magnetron transmitter which he.d a tuning range of 8 to 12 ems. and the calibration was sub_ stantially constant over this range. According to Beggsl55, a series of concentric line load lames have be en developed to meet the demand f or Bother indicati ng and measurement lamps that Hi ll overcome the limitations of ordinary lamT>s at microwave frequencies. The lame sizes made to dP-te have an upper frequency limit of 1000 to 3000 mc. at which reliable measurements may be quickly and easily made. At higher frequencies, they are useful for in- d~ catting relative or maximum levels when making circuit adjust_ Pent ~ . The standing 'save detector or indicator is a snort Mensa_ Agile instrument for development and measurement 'cork. Measurements of complex impedance and standing wave rati o of transmission line loads, of attenuation and characteristic impedance of the lines, and of net Dower flow at any point in the system are but a fever of its applications. The theory for determining the power law of detec4Gors, complex impedance, reflection coefficients of cable connectors, micro~^~ave_cable attenuation, and net power floor is Presented by Feikerl56. He likewise dlecueees the structural features of the standing Have indicator for both coaxial and wave guide systems. The effect of Probe Penetration upon the standing Grave Pattern has been investigated by Altarl57 and his associates. They show that distorted patterns observed in standing wave de- tectors vrith deeT'er Probe penetrations are attributable to r-e_ Elections from the probe wire, and that the probe, over a Pride range of penetrations, acts as a slmnle shunt admittance across the transmission line. The mathe~natlcal treatment developed gives a satisfactory account of observed probe patterns and enables exact readings to be obtained even from badly distorted patterns. Applying their results, the sensitl~rity of standing wave measure_ mental at low_nower levels may be improved without loss of accuracy by using much deeper probe penetrations. A dl~ectlonal coupler is a very useful microwave device wElch has a number of applications such as, for example, monitoring _ 30

the Dower in a trar~emission line, tapping off sonae of the energy in a~ transmission line and conversely injecting energy from another ~ ource into a transmission line, and the measurement of small or moderate standing wave ratios. The frequency range over which moat types of directional couplers will operate is rather limited. This is especial ly true of Brave guide couplers since the impedance of the guide changes smith frequency. Earlyl513 has described a new type of coupler which employs a. small loop that responds to both the electric and magnetic fields. When used in conjunction with a special section of ridged wave guide, it is possible to obtain excellent directional characteristics over a 2 to ~ frequency range. TI E3. Microwave Resonance and Aberration Phenomena . The development of radio_frequency sources and techniques in the con. ~rave-length range has made possible the observation of resonance phenomena of considerable interest in molecular structure. Numerous pioneers, who there fortunate enough to have access to micro~.ra~re test equipment, are already e=loring this never field of microstate s~3ectroacopy. Microwave resonance phenomena fall in Intro categories, tho se associated ,^.~ith electric moments, and those associated with magnetic moments. Although this reviewer is con- cerned primarily Irish dielectri c phenomena, the arriver is taking the liberty of including a brief discussion of magnetic resonance phenomena because of its physical and structural imD1ications. During the war, an unaers~Ganding of microwave resonance and ebso~tion in gaseous media wee of vital importance since these processes effect radar tranamieelon in the atmosphere at certain wave_lengtha. Consequently, the adsorption of cm. waves in atmospheric gases has received considerable attenti on. There are now two known contributions to this absor~tionl59,16~0; oxygen, which has a bard of abeo=tion lines in the region of 0.5 cm. sunerimoo.sed An a weak continuum extending up TO long wave_length; and water vapor, Rich has a weak absorption line at apnro}dmatel5r l.3 cm. and a number of stronger lines below 0.2 cm., the tells of which contribute to the absorption in the cm. ~rave-1ength region. Both of these adsorptions there Predicted theoretically by Van V1eck in lo42 and their absorption coefficients there calou1ated subject to experimental determinations of the line widths due to collision broadenix~gI6l, 162 and some uncertainty in the ~ onion of the crater valor resonance. lIainer, King and Crossl63 have ce~cu'.ated the exact values of the energies and transition ~ro- babiJities of Her valor and. have determined the position and intensity of the absorption in the micro,.~a~re region. The microbe absorption by Boater valor has been deter_ mi ned experimentally by various in~restlgators. Becker end AutlerI64 have measured the water valor absorption line resulting frown the rotational transition Q~_6_5. Microwave radiation eras fed into an air_fi] led cubical copper cavity ~ ft. on an edge. Strings of thermocouples earth alternate ,Junc~cions coated Edith " 1 osey'' mater) a,1 were placed at random in the cavity. The enf _ 31 -

of these ~chermocounles is ~roporticha1 to the Q of the cavity arid its. contents. With the total Pressure inside the cavity at 1 atm., the na.rtia1 Pressure of Rater vapor was varied from ~ to 55 mm. of mercury. A measure clef the change in emf wish h~miclity yields a Prague for the losses in the strafer van or ~ro- ~rided the 0, of the cavity is known. This Q may be determined from additional measurements taken '^rith an aperture opened in the side of the cavity. The ,^!ave-:Length range between 0.7 cm. and ~ .7 cm. has been explored Their results indicate an ate_ sorption peak at 1.54 cm. and a. broadening of the absorption ~ ine as the crater vapor density is increased. It is pointed out that the cross section for a HOBO - E2O collision angst be nearly 5 tins that for a R;~0 _ air collision to account for the observed change in band width Keith Orator density. The peak attenuation eras found to be 0~025 db/ki~ome~cer for ~ gram of water Orator ner cubic meter. . Eyhl, Dicke and Beringerl65 have determined the atmos- r~heric absorption of Beater vapor indirectly by measuring the thermal radiation from the atmosphere using the microstate radio_ meter of Dicke)66. With the addit ion of the humidity and tem- ~erature obtained from ~netearalogical soundings, it is possible to determine the absorption of the entire etmos~here, and to senara4Ge the c ontribution due to Plater vapor. Measurements were made at ''ave-1engthe of 1.00 cm., 1.25 cm., and 1.50 cm. From the observed values of the atmospheric attenuation due to Grater razor at tines e vrave-lengths, it Ala ~ deduced that the abs orb on line centered at ~ = 1.34 cm. has a width of 0.~l cm.~~. There results are reported to be in fair agreement Irish those of other observers. The observed line '..~dth and position are in agree_ rent with Tan VIeck' ~ theory, bug the absolute absorption ob_ served is greater than predicted. Townes and Mer~ittl67 have likewise detected the water vapor line reported in the above papers and have measured it for Pollee water at Dressurf?s near 0.l mm. Hg. AN this pressure, the line is a few megacycles Deride and the resonance frequency can be measured thigh great accuracy. The agreement between these low pressure measurements and the da4Ga of Becker and Autler appears to be ''ithin the combined e~erimenta~ errors in all cases. The agreement in the redone nce frequency f or the Beater vapor line at log and high pressures is Curtis ingly good. Townes and Merri tt have also found one of the several EDO lines predicted near ~ cm. ,~ave_lengt~hs by Weiner, Ring and Crosel63. Beringer368 has reported the results of absorption mea.~uremen4Gs in the 0.5 cm. weve_length range for oxygen alla ox,ygen_nitrogen mixture as a function of pressure. The measured values were found to be in agreement ith the theory of Van VIeck both Irish regards to the absolute value of the adoration (which is as great as 67 db/km, at the band center for pure oxygen at a tore of ~ axiom.) and the aenendence on pressure. . . Hershtergeri69 and his associates have investigated the absorption spectra of a variety of gases at rnicro:'ra~re frequencies. _ 32 -

The absorption coefficients and dielectric constants of 16 gases here been mea`~u~ed ~t two wave-lengths, lo- 1.2,4 cm.. and ~ = 3.18 cm. The gases are H2S, COS, (CH3 )~0, C;~H.O, C2HsOl, SO2, N}I3, Six halogenated methanes and three amines. It its claimed that absorption coefficients as small as o.2.x10~4 cm.~] can be detected and ~ arger coefficients can be measured with an accuracy of ~ 5~. The measured dielectric conetan~Gs at these wa~re_1engthe are es_ Gentian By equal to the static values. A quantitative interpre_ tation of the absorption coefficients in terms of the known structure and sr~ec~cra of the individual molecules is given. The theory in- dicates that all non-~lanar molecules which cossese a permanent dinol e moment should shear a~r~reciab~ e absorption in the microwa~re region. The energy absorbed by the gas from the microwaves re- a~nee~re as heat and sound. Experiments demonstrating these thermal and acoustic effects attending the absorption of microstates by games ore described. Amrnoni a gas ha ~ be en known fair ~ ome ~ i me ~ ~ exhibi ~ a strong ab,ror~tion bend in the region of 1.25 cm. ~.re..,re_le~;ths which is associated. ''rith the inversion of the ammonium molecule relative to the alone of the hydrogen ascots. At re~ati~re~y high Treasures, a single broad absorption band is observed. Recen4Gly, a number of ex.ce1.] ent determinations have been made at reduced pressure of the fine structure of this inter on band. Ex~eri rents were r,er- rormed independently by Bleaney and Penrosel?O9 by Townes1-71 and by Gocd772 and are a? 1 in substantial agreement. BY eaney arid Penrose measured the absorption over the pressure range 600_0.2 ma. Eg. and resolved the anionic spectrum into at least 20 obeer_ va.bJe lines at low pressure. The line breadth was found to be ro~ort, onal to pressure and indicates an effective diameter for .. . . collision_broadening of the ammonia mod ecule 3_5 times larger than the usual ~re'.lues. This behavior is attributed go the large external field of the molecule. Townes has also resolved the in- version lines near 1 .25 cm. , their widths being decreased at ~ ow pressures to 200 kc. Line shapes, intensities and frequencies were measured and correlated Bath theory. Ca~cula~Ged intensities and the Lorentz-tyr~e broadening theory fit the experimental re_ suits if the frequency of collision is 15 times greater than that measured by vi sco~ity methods. S~1 ingoing due to rotati on is in fair agreement with a -recalculation of theoretical values. Hadley and Denni~on 7-73 have likewise recalculated the splittings in an attempt ~c ~ obtain better agreement between the ory and observations. Tonnes has observed a ~a~Guration effect with increase of power absorbed per molecule and has offered an interpretation of this behavior. Good has observed 30 lines of the fine structure of ammonia in the region of ~ .25 cm. He measured their intensities and frequencies for two different temperatures and deduced an empirical expression for the line frequencies in tenures of their rotational quantum numbers. At pressures of 5~10~ mme Hgo and below,, the lines are very well recolored and at ~re~.Qures of lo-2 moo fig. and below, e. definite hy~erfine structure appears. Good has also observed the Stark effect on applying a. d.c. field to the absorbing gem. - 33 -

The hy~erfine structure of the ammonia spectrum was explained slmultaneQusly by Coles and Goodl74, and by Daileyl75 and associates. Cores and Good.have resolved a hyperfine struc- ture ~ n most of the rotational lines of New H3 and lnte~ret the structure as a splitting of the ratatior~al energy levels by a coupling between the angular momentum of the molecule as a whole and the spin of the nitrogen nucleus. This Interaction appears Go result from an electric quadrunole moment of the N74 nucleus. tI)5lI sho',rs no trace of hyperflne structure since N15 has a spin of i72. In order to test the quadruple hypothesis as an Lana_ tion for the hy~erfine structure of N14ES, Dailey an] his asso_ clates have carried out e. quantum mechanical treatment of the ~ nteraction arid the results ~Are-~e compared with accurate measure_ . . meets of the hy~erti ne structure . Excellent agreement ''as ob . tained. It Alas concluded the t the hypothesis that the hyperfine structure of ^tT~4R is caused by a quadrupole interaction is strongly au~orted by several types of observations. Codes and GoOdi74 have observed Stark Ed Zeeman effects in the microwave sneci~r4um of NHa in the 1.25 cm. regi on using }~3 containing both ~ and N15 isotopes. A magnetic field of 6600 oersteds applied perpendicular to the high frequency f ieJ d splits a rotational line into a doublet with ~ separation of arrow - rely 2.0x10-4 cm.~1 independent of J and R: within ex_ experimental error. A magnetic field parallel to the high frequency field produced no observable effect. The type of structural information Chant can be obtal ned by micro are a~ectroscopy is demonstrated by the investigations of Dakin, Good and Co'.eal76 and clef Townes, Holden end Merrittl77, Dakin and his co17aboratore have resolved the absorption line due . to the transition from the ~ - 1 to the ~ = 2 molecular rotational level in the OCS molecule. This line appears at 24,300 me; and was resolved at pres sures leas than 10- En. Hg. At greater pressures, the pressure broadening of the line was so great that the line was hardly ob.ser~rable by their oscilloscope method. The moment of inertia of OCS calculated from the above frequency if, 1.379x10-38 g cat , which agrees well with the Prague 1.3RxlO-~ g cant , calculated using the interatomic distances observed by cross and Brock'.ray. A linear molecule of this sort should show Stork effect and solltting Proportional to the square of the electric field strength and the square of the dipole moment. Ashen ~ d. c. electric field eras applied ~Go the OCS gas in the Grave guide with the d.c. fiel] parallel to the direction of the Polarized electric vector of the t-ravelling micro~ra.ves, the rotational line Split into two lirtes; one snored to a Coffer frequency, the other to a higher frequency than that of the unperturbed transition lines The equation relating the frequency of the two lines to the moment of inertia, the a. c . field strength and the dipole moment is given. The dipole moment was calculated and found to be 0.72D comparers with the brogue of 0.65D -reported by Zahn and Ail es from dielectric constant data. - 34 _

In the experiments of Tourney, Holden and Merritt, the rotational spectra of several line an Molecules were found in the region near i cm. wave-length at pressures of the order of ~ few tenths of ~ mm. Hg. of the absorbing gas e In some cases, a num- ber of weaker ~ ines were ford to accompany the main rotational line. The measured frequencies and intensities of lines in the rotational spectra of Br ON, ClON arid OCS are tabulated. The C1CN likes at 23,885 and 23,389 mc. appear to be caused by C135CH and C] tCN molecules respectively which are in the ground vibra_ tional atate and undergo a ~Gr=sition from J-l to J=2. Similarly, the BrCN lines ~ 24,712.5 And 24,570 me. are a~GIributed to the molecules of Br YCN and Bra ON respectively in the ground vibra- tional state which make a transition from J=2 to J=5. The single OCS line is caused by the rotational transition J=1 to J=2. The moments of Iberia are computed. Using the isotople frequency shift in CICN, the internuclear distance C-N is cat culated to be 1.15 I. The isotonic shift in BrCN is also consistent with thi ~ Prague. The internuclear bond distances Br-C and Cl-C were also calculated. All three distances were found to be in good agreement with electron diffraction measurements. These data can be used to distinguish between alfferent possible structures f or these mol ecules . The data are consistent with the structures Cl Cat and Br-C-N but not Perish the structures Cl-N-C and Br-~-C which have sometimes been proposed. In the firing paragraph of th' ~ section, it was stated that microwave resonance phenomena fall into Into categories, those associe.ted smith electric moments and those associated with magnetic women; The microstate resonance and absorption pheno- mena discussed so far Perish the exception of that pertaining to oxygen once their origin to the existence of a permanent electric moment. The microwave absorption by oxygen gas on the other hand is due to its magnetic moment. The remainder of thia action Trill deal Perish magnetic resonance Phenomena. The permeability of ferromagnetic materials at fre_ quenches between 105 and 10 0 cycle a per sec. wee investigated by Allanson'78 . Methods of measuring the permeability of ferro_ magnetic materials in high frequency fields are described and the resul ts obtained by various investigators are correlated and discussed. It appears that hysteresis effects cease between 10 and 107 cycles per sec. and that the ~ermeabi, ity decreases with increase of. frequency until 1 t reaches unity it, the region of 10 cycles/sec. Various explanatory hypothesis are discus Bed and it iB cone] uded that the most Probably explanation is that the phenomena are due to eddy currents Erich delay magnetization roceases. These eddy currents are caused by the extensions or rotations o' the magnetic domains and act so as to slow down and finally prevent these changes. The theoretical data evaluated on the basis of this hypothesis are reported to be in good agree- ~nent smith experimental observations. Eittel}79 has proposed a theory for the dispersion of magnetic Derineati~ity in ferromagnetic materials at microTralre frequencies. The transition in the Prague of the initial _ 35

permeability of iron and nickel frown the d.c. value ~ ~ 100, go the infra red, TV = 1, is known to occur princinaily in the microwave region. An explanation of the experimental facts is proposed by c onsidering the equation of motion of a domain boundary ~ n an applied magnetic field for frequencies such that the skin death of the magnetic field is smaller than the thickness of a domain. An analytical solution of Maxwell' g equation is found for the r~agnetiza~Gion of a layer one domain thick. The definition of the permeability at high frequencies is considered carefully and it is shown that the natural definition leads to c complex values for the permeability. In experiments, two different types of are found. The relationship of the complex ,~ toters determined -from resistive losses in a circuit elements and toils, determined :from reactive changes, is developed. The status of Becker s theory of eddy current damping is considered and several suggestions are made for further experiments. The electromagnetic properties of ferroso_ferric oxide end ganuna-ferric oxide have been investigated by Birksl80. The oxides in nodder form were mixed in various proportions with a loll :08B, non-magnetic binder~p~affin wax). From measurements on nicer es up to 5040 concentrati on at three wave_lengths, it alas found that the complex ,~ varies with ~ (volume Proportion of oxide) in accordance with the theoretical Clauslus-Mossotti re7~.~on: - _ vail ~+2- ~Fa+2 whereby is the complex ~t of the oxide extrapolated to 100< con- centratlon. The derived magr~etic ~ropertles of the two oxlde8 are liated and the real and imaginary components of Ma for r-Fe~O3 are plotted together with ROttlgls data on the solid oxide for ~rave_lengths from 39 to 174 cm. Both oxides show ma.gne tic disperse on accompanied by a loge ma~netlc abortion. For r7-FeaO, maximum absorption occurs at a ~^ve-length in the neighbor- hood of ~ a cm. The mechanism of nuclear induction has been investigated independently by Purcell and 0a co-workers and by Block and 0a associates. PurcelliS] and his co-workers in a letter to the editor of Physical Prier report observat;ione of the transitions between energy ~ evels corresponding to different orientations of Proton spin in a conatar~t magnetic field by measuring the absorp_ tlon of r.' energy in solid paraffin. Experimentally, a resonant cavity witn a resonance frequency of ap~ro:~lmately 29.8 me. was Placed in a strong magnetic field, the inductive part of the cruelty being frilled with paraffin. On verging the static magnetic field, a very share resonance absorption was abeerved at a field of 7100 oersteds giving ~ value of 2.75 nuclear ma~netons for the magnetic moment of the Proton which is in good agreement with the accented value . The relaxation time was found to be les ~ than 1 minute thus bet ng several hundred times smaller that would be deduced from the type of ~i n-la~ctice coupling sugges'G by Waller. Torrey, Purcell and Pound 2 Presented parers on The Theory of _ 36

Magnetic Resonance Abduction by Nuclear Moments in Solids and Measurement of Magnetic Resonance Absorption by Nuclear Moments in Solids at the Cambridge meeting of the Physical Society. More recently Purcell:83 and his associates observed nuclear resonance absorption in hydrogen gas at room temperature and at pressures ranging from 10 to 30 atme. The - resonance eras found to occur at the frequency and magnetic field strength corresponding to the "g" value for the proton but the process involves both protons in the ortho_hydrogen molecule only. A single extremely sharp resonance line was observed, the width of which remained constant at 0.25 gauss over the whole ~,ree~ure range. The intensity of the line was found to be directly proportional to the gee pressure. The nature of the relaxation mechanism is discussed. Purce11184 and his associates have also investigated the resonance absorption by nuclear magnetic moments in a single crystal of Cafe. The magnetic di~ole_dipole interaction between nuclei arranged on a cubic [attic in the presence of a strong external magnetic field, lIo, depends markedly on the direction of lIo, with respect to the lattice aces. If the width of the r.f . absorption line at ~ = ~Ho/Th arises mainly from this interaction, the width and ale b the peak intensity of the resonance absorption observed in a suitable single crystal should vary as the crystal is rotated in the field, lIo' Such an effect was found in ~ single crystal of fluorite, Cafe, in which the magnetic nuclei occupy a simple cubic lattice. As pointed out previnusIy, Blockl85 and 0a co-workers have carried on an independent investigation of nuclear induction using a Someday different experimental procedure. The magnetic moments of nuclei in normal matter uroduce-nuclear naramagnetic polarization upon estab~ ~ shment of equilibrium in a constant magnetic field. An r.f. magnetic field applied at right angles ~ ~ the constant field causes ~ forced precession of the total polarization around the constant field wi th decreasing amplitude as the Larmor frequency approaches adiabatically the frequency of the r.f. magnetic field. Thus there results a component of the nuclear nole.rization at right angles to both the constant and r.f. magnetic fielde. Block has shown that under normal laboratory c onditions, this component can induce obser~rab, e voltages which can be detected in a cod] vrith axis perpendicular to the two fields. Block gives a discussion of nuclear induction considering first the external fields only and then those modifications which ori- ginate from internal fields and finite relaxation times. Bloc3: and his associates heave carried out experiments in which the signals from Protons contained in a variety of substances severe observed. The results show the role Played by the relaxation time, which was found to vary between about 10- sece. and many seconds ~ The phenomenon of naramagnetlc resonance has been in- vestigeted by Frenkel, by Za~roisky and by deVri jer, Volger and (sorter. Frenkell86 has extended Rabits theory of magnetic resonance to the case of the existence of friction; forces and applied it to the calculation of magnetic lo9 see in a solid _ 37 -

diamagnetic material for the case of a high_frequency magnetic field Perpendicular to ~ strong constant magnetic field. The dependence of these los see on the intensity of the constant field or the frequency of the r.f. field is in agreement with the ex~eri~ mental results of Za~roisky. Frenkel Choirs in cor~clusion that the total broadening of the resonance line must contain a term ~ro- nortiona~ to the square of the ratio of the rift field strength to constarlt field strength. The diamagnetic absorption of energy by OUC18 SPIRO, CUSO4.58;10, OrCIB, and MnCO3 WEE investigated by Zavoiskyi87 in a constant magnetic field Perpendicular to an r.f. magnetic field having a frequency of 1~51xI0 eycles/sec. The results of these measurements are discussed from the standpoint of Frenkel' ~ theory of snin-magnetic resonance. dettriJer, Volger and Gorter]87a have measured the reef. paramagne tic absorption of gedolintum sulfate oct~drate al 77o and 90°K. in order to obtain an indener~der~t determinati on of the specific heat of the spin system -ma of the lattice relaxation constants. The value of the win relaxation constant obtained is in good agreement with Brc~er'~ thearetica1~ Prague of 2~5 :~: 10~ 0 sec. A new magnetic resonance in ferroma~gnetl~ materials at microwave frequencies was discovered by Grifflths 88. Grifflths' e:gneriT~nta are analogous to the nuclear lnductior~ experiments excel the t the phenomenon is dus ~Q the absorption of Or.. energy by Recessing electrode and oc cure in the microwave region for static field strengths comparable to those in the nuclear induction experiments. Griffithe found that the resonance fre_ quenches he observed were greater than the calculated Harmon frequencies for electron spin by fact ore of about ~ to 6. RittellB9 has given a theory of this resonance effect which leads to values of the resonance frequency in close agreement with the expert_ mental determination. He shored that it is important to consider the dynamic coupling caused by the demagnetiza~Gion field normal to the surface of the teat specimen with the result that the appropriate Labor frequency should be calculated as for a field strength (BH)~/2 rather than -or H. Furthermore, by introducing a damming term, Rittel has derived an expression for the compl en permeability in the direction of the r8 me- m~etic field from Rich 'Ghe apparent permeability,~L6r, can be calculated. Hughes igO has proposed a new method of measuring the electric dipole moments and momenta of inertia of diatomic polar molecules. The moQeculee of a molecular beam are caused to under- go a transition in a steady homogeneous electric field by an oscillating electric field at right angles to the deco component. This experiment is, therefore, closely analogous to the magnetic resonance method. Hughes considers the new method ~ advancemer~t over previous Methods in that a single rotational state of the molecule is studied even though it is present to only one pairs in 10,000 as a component of the beam. The dipole moment and momer^t-of inertia of. cesium tInoride were determined by this method. A feature of this method in common with the magnetic resonance method is its extraordinary resolution of close energy levels which so far exceeds that of infra_red spectroscopy that _ 38

momenta of inertia may be obtained for heavy molecules which have previously been beyond reach. In contrast to solution methods in which the variation of dielectric constant is measured as a function of temperature, this procedure gives the dipole moment entirely independent of mass interference effects. [I ~ o Practical Applications In the first part of this Digest, the emphasis is placed on the theoretical aspects of the electrical properties of matter and measurement methods for inveatigati ng the se properties . The reduction of dielectric the ore to practice is of equal, if not greater, importance. However, an extensive treatment of this sub lect would result in a sizeabl;e addition to art already lengthy review. Furthermore, other parts of the Digest will undoubtedly deal with the practical applications of various dielectric ~naterial;~. Consequently, the discussion in the present section will be limited to Dielectric Heating, Coaxial Cables and Transmission Lines. ITIA ~ Die ~ ectric Heating ~ _ The introduction of electronics to industry has brought about many outstanding improvements in production and quality durtry; the nest few years. Among the more important of these achievements are those Chose effectiveness depends on the use of electronic heat which may be aped fed in two forms, induction heating and dielectric heating. Only the latter form will be c onaidered in thi ~ reviewer. The development of dielectric heating has been rapid in the la8t fe,¢ years and much h" been written concerning the fundamental principles of dielectric heating9 the d e s i ~ of hi gh-fr eque no y he alp ing equipment and the applic at i on of dielectric heating to various processes. The literature during 1946 has again been voluminous. Maddock:9] gives - an account of the modern theories of dielectric behavior so that the mechanisms of dielectric heating many be understood. There is also a section on energy and power red ations and the choice of frequency. The final section is devoted to the practical aspects including a discusaion of tem_ Denature distribution, applications of dielectric heating and miscellaneous notes. This article cites 21 references. The basic factors in dielectric heating are set forth by Winiund ]92 in the form of equations, tables and charts; trio graphs for com_ outing the poorer required per 100°F. temperature rise for given 'heights of materials of various specific heave are presented by Bocki93. Oebornl94, Hartahornl95, and Cablel96 have published revere on High Frequency Heating and Tinnerholm)97 has an article on High Frequency Preheating. Nielson)98 considers the question as to 'chat frequency to Ale for induction and dielectric heating. An erticl e by Bosomworth:YY discusses the theory of die] ectric heeding, applications in general fields, applications in the rubber industry, radio-freauency curing, Ogle Or equipment re- auired, choice of frequency, radiation measurements, screenings _ 3g -

material handling, temperature control , maintenance of equipment, ant testing instruments required. Prob] ems in the design of hlgh-freauency heating ea~uip- ment are considered by Roberda200 and Reifel 20] describes an auto_ acetic tuning system developed by the s~cevene_~nol ~ Co. , Inc . , and Enrich comprises taco servomechanisms for varying the coupling be- tween the load circuit and the oscillator tank circuit and for tuning the 1 cad circuit; to resonance as the effective load im- ~edance varies. Another coupling method is described by K1 einberger202. Xohier203 deals Ah the- heat sealing of Atlantic films inc] uding such items as the danger of overheating, the mechanical eaui~men~G and electrodes, electrode design, equalization of pressure, a good weld, valuable design factors, operating fre agencies and the necessity for a well filtered power supply. Another arts ale on segl],r~g ceJ Europe acetate with high-frequency was Smitten by Coiner. Seal ey205 describes the application of dielectric heat in mold' ng ins-A1a~Gion. are: Other references to literature on dielectric heating Radio-frequency dehydration of penicillin solution Bro`.'n206 and <ethers. Dielectric heating of granular materials. Aluminum and silicon oxides - Schutz and McMahon207. Electronic he ating in the furniture industry High-frequency en ectric heating. Some notes on its industrial a~licati ons209. High_frequency heating de~relo~nenta2~0. Dielectric heating equipment su~r)liee heat go cure f cam rubber. Dielectric heating dries and cures rubber21 2. - Winalund203. Electronic eouiument to preheat molded material preformable. Electronic rubber preheater - Mittelmann and Bo~o~nworth214. High_frequency heating conference215. Induction and dielectric heating formulas23 6 . High_frequency heating in U.~. plastics ~ractlce - Brumleve217 Reating and vul canizing rubber and simile; resins with high-frequency cur-rent - Smithers (3. _ 40

Case studies of RF heating. Modern methods of using hi gh_f requenc y he e.ti ng 219. High-trequency head cures Foamex producte220 . Radlo_frequency a.c. current acpl fed to industrial he'atlngZ21. Dielectric heating dries transformer bushings _ Cole222. Dielectric heating analyzed for textile auplications223. Electronic machines to Join thermoplastic sheet mater) a, ~ 224. Electronic heat. Neweat in electronic heating is a unit that sprays r.f. energy onto the ob ject to be heatea225. Electronic blowtorch226. Induction and d' electric heating data. Dielectric he ating f ormu~a'; 227 . Industry Cooke wi th electrons _ Stimson228. Dielectric machine to preheat molded plastic fief ormS229 Electronic2geating equipment to preheat plastic molding Beef ores 0 AFO f or R ~ F. he ating - Rambo23i ~ Induction and die1 ectric heating232 R.F. heat ~ aboratory 33. TIlB. Coaxial Cables and Transmission - Lines . . . Coaxial ~ abl es and transmission lines are an important component of high-frequency and micro are equipment. Considerable devel opment work Moran carried on during the war especially on the design and production of low_loss flexible solid dielectric coaxial cables. A discussion of developments in solid dielectric r.f. transmission lines, including sections on polyethylene, types and design of cabs es line efficiency and available cable types is given by Jraham234. ,1arner235 has written an excellent article clearing Erich the problems encountered in the manufacture of ult-ra- high-frequency solld-dielectrlc cables. The various types of semiflexible solid_dieJectric transmission lines suitable for use at ~f are discussed and five general types are described. These are (a) coaxial, (b) dual, (c) dual-coaxial, (~) lo''_ capacitance and (3) high impedance. Types (a) and (b) are genera' r~urnose lines Anile type (c ~ is used in direction find' ng equipment, instrmnent-landing systems, etc. ETigh impedance _ 41

cables fi nd use in cathod e_follower and special delay circuits . The manufacture and problems associated Perish extruding Band braiding are considered. The question of penetration of the braid into the- dielectric and ',~.cket a=d the recent steps taken to eliminate this probe em are discussed. The contribution of the individual com- ~onents of the cab] e to the to~Gal lose is examine and an apparatus de scribed Enrich e nable ~ ~ direc ~ me Deuce ment of bra id re ~ i ~ tanc e to be made at 150 mc. A typical example is given for R=~/u cable showing c~ ore agreement between the measured total loss of the tires and the lose obtained by a summation of the individual dosses of cry el ectr'c, inner conductor and braid. The effect of varying the braid c ons true ti on ~ ~ demons trat ed . Finally, a brie f de ~ crtr'- t i on i s gi ven of the vary ous t e s t s and the e quipm2e at f or t e s t ing ht transmission l' nest In another later, Warner 3 c insiders the choice of ¢~ecketing; materials for high-frequency trane~ninsion 7 iH=8e According to ECr7'eger and Raabe237, few manufactured products eve flub ject to the elaborate and extensive tests through Much EGOS yethylene dielectric cabs e is but, in order to insure its uni- 'c~m que.lit.y snd performance. Strict end_to_end uniformity is me' ntained throughout the entire manufacturing process. This is accom~7 ished by prec'sion-extrusion, accurate temperature control , constant Process inspection and micrometer gauging standards. A discussion of oo:~ye~Ghy~ene dielectric cables is also given. Krueger also has a Caper on flexible coaxial cable2~. A brief account of the cables used in radar equipment with spect~.l reference to ~olythene (polyethylene) insulated types i ~ Presented by Smith 239. The rf characteristics of radar cables are determined by Resonant lines and nstanding wave" methods. In anion to the rf tests, all cable is subject to d.c. measure- ments to determine conductor and dielectric resistances, the 'ester being usually at least 105 megohms/LOO ft. A high voltage test at 50 cycles/sece is also applied, the frontage chosen being such that the maximum stress in the dielectric ~ B 90 kv. (~eak)/cm ~chneon240 testis with the development of a low_loss 300 ohm Parallel Are polyethylene transmission line. Loss curves as well as a Photograph of a production run. sample of line are inc luded. Design data and cheracteristice of high-frequency cables are dealt with by zimmermann241. Design data for beaded coaxial lines are given by Cox242. A note concerning a coaxial design, gas _ f ~ Iled e le c tri c c able f or hi gh-f r ep uency c irc ui ~ ~ apse ar in Industrial Equipment Ne~re245. Oraggs and Rant er244 derive mathematically the capacity of tin cable. A cable with an im- r~edar~ce of lOOO ohms ~ ~ described by Kalimann245. Tt resemb, es the usual flexible concentric cable but its inner conductor is sing~e-~ayer coil continuously wound on a flexible core. A lo~'r_los~ coaxial line called CO-X using dielectric filaments be_ tween ounces and inner conductors is a new product of the Boston Insulated Wire and Cabs e Company246. The principles used in _ 42 -

calculating the temperature rise in cables for transmitting rf power ere cons idered by Mildner247. The theoretical attenuati on che.racteristice and power ratings of a number of standard rf cables are get down in graphical form for a wide range of opera_ tiny frequencies. The effect of the presence of standing waves and the effect of end cooling are considered in relation to the rating of the cable. :~:= I: ~ A discussion of the characteristics and a~nliceti~ns of Fiberglas to ''ire and cable ~ nalllation is given by Sam~son~48. The basic charecteristic6 of Fiberglas yarn are incorporated in many commercial! y avai ~ able cables today. Fiberglas insulated magnet wire has been produced now for many years and is an es_ Ad. . . tablished product in the electrical industry. Fiberglas lead wire, resistors, radio hook-u~ Refire end ignition ce.bl e are also familiar commercial products. To meet the demand of many ~nli- cations where an ins :lator is needed to withstand operating tem~era~:ures of 1000°F. or more, Fiberglas textiles are especially processed to make them heat stable up to 2000°F. In the electrical field, Fibe;rgIes special high temperature tace and sleeving have been used experimentally with considerable success airy these materials can be furnished in limited quantities. This material, hoverer, is not recommended for applications where severe flexing or Technical abuse is encountered since no imoregnant is used. Increasing interest in the electrical industry in the superior properties of Fiberglas-silicone combination materials has resu1 ted in considerable de~reloc~nent work. Silicone-varni~,h- im~re-gnated FibergIas-covered magnet wire is being produced on ~ semi-comn~ercial scale by several manufacturers. Laboratory work is being conducted on cable constructed with a silicone-rubber extrusion over the conductor followed by an outer Fiberg] as braid impregnated 'pith silicone varnish. Also in the development stage is Rework on the application of Gil icone v~rni shecl Fiberglas Cal oth applied as cable fare '.~ma~. The superior electrical Properties, resistance to high temperature and to moisture and the ~erma.nence of Fiberglas and silicone combinat;ions warrant further development work and u711mate3,y co~r.mercia~ e.~lice~rions in the wire and cable industry ,~l be ~ rea~itye various other applications or noten- tia' e.~3 icetions are cited in Sam~non' ~ cater. The manufacture and use of p;1 ass_bonded mica are described by Re~lo~le249. An article or In.3ection_~1ded G3~-Bonded pica Reared in Elec . Meg. 250. An improved glass_bonded ~nice.- (mycelex 410) provides a lo'.~!-1oss insulating material for injection molcsi:~g. It; hoe been developed for ~ arge_run production of small elec~Grica] serfs D~r~:icu~arly in irregular shares. Molding tech- nioues permit irco-r~ors tion of merges inserts of bras =, courter, steel, nones,, etc. and result in smooth mold first sh end erect si on tolerances. The electrical characteristics of this material make it ~ticul~rl y suitable for high-frequency ep~licat;ion~-. There a - 43 _

low_]oss factor ~ ~ .016 at ~ me. ~ is required or for applications where it is e~sentie7 to Iran high voltages without car-oon1- ~ation in the ever of arcing. The electrical Properties are: Power factor tory at ~ mc. ~ - 0.0015, £' (1/~c. 3 _ 8~3 volume resistivity _ 6.0xlOi ohm cm., dielectric strength _ 400 volts/mil, arc resistance, A. Be TeMe ~ 250 see ~ The replication of insulators in contaminated atmospheres ~ s considered by Frey25l. IV Elect;r'cel Measurement Methods The methods and equipment for making D. C. and loller fre_ cuency measurements are now fairly well established e.nd stanc~ar- d' zed* The conventional t'lum~ed" circuits, however, become in ectical at frequencies much above 100 mc. and. the experimenter must work with transmission lines and resonant charities. He snuck, therefore, become familiar with transmission line theory and the fundamental ~rinci~s of microstates as d.iscus~ed in Section IT E1o Several ~ e ~ methods for microwave measurements have been described in the lit endure for 1946 and several other methods developed d. urtr~g the war have not yet been Published. In this section, the emphasis w'T: be Pieced on n~cro~a~re measurements since they re_ Present the most recent developments and are ~erha~e unfamiliew to many 'corking in the field of dielectrics. IV A ~ Re ~ i ~ ti vity ~ nd C onduct ~ Measurements A review of the Parlous methods used in the measurement of resistance, from the Simon eat form to the more highly accurate laboratory methods, is given by Litt252. The article discussed severer methods ~ nc~uding the vo~ tmeter - ammeter method, the simple ohm meter, the Wheat: Bt0 ne bridge and the Key vin bridge. D.C. insulation resistance and capacitance measurements are also described by Hutchine253. Dexter254 shores how the resistance of a sensitive d. c . meter can be determined. Polgreen and Tomlin255 decal with the electrical non-destructive testing materials and an accounts of Federal Telephone and Radio article ~ubllahed in Electronic Indus~Gries'~. Mohler and Sternisha257 point Out that conductivity measurements provide a rapid and reliable method for plant control of certain types . . , of solutions such as cleaner baths, acid or alkali rinse waters, din tee the and etc. The application of resistance measurements to oil testing ts diacuseea by Pike258 who cites the Forrest inept ation test set as an enable of a suitabl e apparatus f <:xr thi ~ Burros e . of the Insu? at ion Laboratory of the Corporation is~gi~ren in a pictorial IV B Impedance Dielectric Constant and Loss Measurements A method of making impedance measurement With the c~thoJe_ray oscilloscope is described by Viesere 5 ~ The _ 44 -

measurement of arc. capacitance and induc~G~ce of cables is dealt zenith by Hutchins260 and Rosen261 considers the problem of end leakage in cable power-factor n~easuremen~Gs. The conducting fib of moisture on the surface of the end insulation causes: an error in a.c. measurements on cables which cannot be avoided by the simple provision of a guard Afire. The mains tude of the error is estimated by considertry; each cable end as a transmit sion line. A means of effectiveig eliminating this end leakage error is described. Stamford and Quarmby262 consider the characteristics of or.. cables. They describe a measurement technique for the determinati on of the ~ mpedance and propagati on constants of r.f. cables which is fundamental in principle and requires only He apparatus. The authors point out that this method has now been su~erceded by methods employing more refined techniques, but they fee] that it is useful for certain applications. The tech_ nique is equally applicable to coaxial or t~rin-type cables and the frequency of 600 me. is a convenient one and -~^ HA To determine the ly count ed to an The input current to the line i8 measured and plotted as a function of line length e The chase constant is obtained frons the distance between two succesolve minima of incus current. The n.tten,~ z; to ~ We- Ul1~; 111~13UL'=~r1 bs . phase c onstant, a length of cable is magnetical_ oscillator at one end and left oven at the other. on cons tent of the cable outputs of short; and long lengths of line hay' ng equal inputs. The characteristic impedance of the cable is determined using a simple ve..riation of the arrangement used for the attentua tion measurements. A method for measuring the Velocity of propage.tion in cables is proposed by Kramer and Stolte~63 and an instrument auitab, e for measurements at 100 me . i ~ described. can be found by comparing the Zhilenkov264 has investigated the source of errors in the measurement of the diet ectric constant and absorption by the method of the Mernst bridge over a wide range of frequencies. Wang~gard and Hazen265 have used the Q-meter for dielectric measurements on polyethylene and other plastics at frequencies up to 50 me. Ike detail ~ of the method employed and the Are_ cautions +?~..en to minimize errors are given. A method of measuring complex: resistances in the range of decimeter revel eng~Ghs is described by Knol and Strutt 266. In this method, a. screened Lecher wire System is fed symmetry_ Cal 7 y from a voltage source; the unknown resistance and a `~lidable diode indi cator are placed across the wires . Two ~ riding shorting links simplify the procedure and permit measurements to ye made over a Mae frequency range by cancel- ling the reactance of the source arid directing the reflected wave to,'e.rds the diode. The refl action coefficient is deter_ mined by diode location and yields the real and imaginary Darts of the unknown imnede.nce. The characteristic impedances of concentric, r,aralle] and twin cables '~.^ri~chin different ounces screens ore derived and the ~ nf~uence of the diode admittance - 45 _

on the accuracy of the me Shod is discussed. Hof:'feegen267 discusses severe: methode for measuring im- ~ed~nce ~rticu~arly at decimeter w~,,,ve-~.eng~hs. At wa,~re_lengthe greater then one meter, it ~ ~ customary to connect the unknown iml3edence in ~re.17 e ~ Perish an 3sciila.10r~y circuit and to determine the unknown impedance from the retuning and Clamping influence ex_ r,erienced by the circuit. For decimeter ~ave_lengths, a Lecher system is used s~ the oscillatory circus ~ and ~ diodle vo~ tmeter as Nor. Ire a second barer, Hofweegen268 describes another me Tahoe for measuring impedance which supplements the previous method for decin~e1;er measurement,~. The characteristic feature of this method is the use of a Lecher sys~Gern Which is not tuned to the measure ng frequency. The refl ec~Gion factor can be deter- mined by measuring the ~rolta.ge varieticn along the Lecher system ',-hen it is ~ oa`~.ecI by the unknown impedance. From this measure- ment, the ur~kno~m i=nec-ar~ce can be calculated. Numerous investigators are now making dielectric measurements at very high and microstate frequencies. Many of the Avers airendy cl ted, particularly in section TI Ed, contain descrtr'1ions cuff test equipment eared Procedures used in the various mic~o~'ave investigations. Molov269 has considered the a~licatior~ of wave guides to the Augury of the electr'ce] properties of matter at ultra_high f-~eouenciee and several other Caters deal Greece_ f ically Erich measurement methods and techniques . Horner£70 and his associates cover resonance methods of dielectric measurement at centimeter wave_'engthe. This paper discusses the theory and e~erimenta1 development of resonator sys~ceme suitable for di- electric constant and cooker factor measurements on solid d1- electric materials at wa.ve-lengths below 50 cm. The refire suitability of three forms of resonator, namely, a shorts c' vcuited length of coaxial transmission line overacting in the -inci~.l mode ~ and hollow cylindrical cavity - resonators ope_ retina in the Echo and Coin modes respectively is discussed. The theory governing the resonant behavior of these systems when wholly end partially filled enrich ~ osay dielectric is developed Find the relations connecting 6' and power factor of the die~ec- tric smith the resonant we~re-length and -factor are derived. MacLean27: describes a microwave dielectric loss metering technique which is especial ly good for measurements on very lo~r_Ioas dielectrics. The dielectric loas is measured by determining the Q; of ~ resonator partial 1 y fil led with the We. Double sample technique is used to eliminate dominant ~ ~llriou.s [oases. Metal loss is reduced by confining the field mostly to the ambles The deturling process f or determining ~ is accomplished by a ledge movement of ~ small rod, the Retuning being calculated by the action theorem. ~ The difficul~les filch art ~ e in the m - Inurement of very arne.ll los ~ factors are enumerated. The author Solute out that the method i ~ restricted to the diffic_ uric measurement of small loss factors and will not work for large Toes factors. I~c also requires knowledge of the approximate

dielectric constant. The apparatus used in an experimental test on ~olyst,yrene at e. ~rave_length of 10 cm. is described. Either the TE >~, or TEo~2 resonator modes are used. The design of the resona-Gor and the factors determining the size of sample' size of resonator, and the geometry of the tuning rod are discussed. The J oss factor for the sample of pal ystyrene tested was found to be 2.7 x 10-4 with a r.m.s. fluctuation of 0.1 x 10-4. Mac Lean believes that even better results can be obtained with better equipment. In Ig40, dielectric measurements in the cm. range were considered as difficult and not very accurate. van RiPpel and his associates, therefore, developed a hollow pipe method wilich overcame these objections end required only a Bleak oscil~ ator end s~na7~l amounts of the dielectric material. The publication 0~ their work ma den eye d by Government security rend ations during the war. Roberts and von Hi~pel272 have given an account of the theory and its Practical applications as Quebec ted u~ to March 1941 in a Dater Enrich appeared in 1946. Since 3941 the method and test equipment have been developed to the Point Inhere Precision measurements can note be made. In their method, a transmitter radiates wearer of a given frequency into one end of ~ closed Cave guide; they are reflected by the metals ic boundary at the other end. Standing ,^raves ire ~ et up and can be measured by a probe standing Are detector trave1ling along a slot in the Dine Parallel to its axis. The dielectric is inserted in the closed end of the pile opposite the transmitter fi Iling the volume to a height 59 and the wave pattern above it is measured in air. The dielectric constant and loss factor are ca.Iculated from the vol_ Cage standing scare ratio and the distance xO, of the first node from the surface of the dielectric. The mathematical theory of the method is given, the structural details of the apparatus are described and ~ Cone resul 4~s aid ~ wave_len~;th of -6 cm. are gi ven to illustrate its performance ~ Since 1940, more accurate date. at ~ = 3 cm., ~ = l:) cm., emd at longer ~a~re-lengths have been obtained for ~ Deride variety of dielectrics in the Labor&tory for Insulation P-esearch at MAT. These results are summarized in two volumes - Tebles clef Dielectric Materials _ prepared uncl er 0. S.R.D. Contract Oh~ar_191. The analogy between Lecher lines and wave guides first suggested by Schelkunoff (1937) and later developed by Flint and Pincherie (1943) hers been used by Wilkins and Bolton273 to derive ~ rare guide method for the me~.~-ement of the ~ronerti es 04 dielectrics at very high frequencies. Experimental results are given which support the theoretic al c one lusi one obtained using the ?.. ogy. Basically the method consists in terminating ine (coaxial or Breve guide) with a merged Ante end measuring the impedance of the dielectric fill ed guide Enrich the dielectric in contact Parish the end elate and s.1 so been it ~ ~ moved ~ die fence of one quarter we.ve_1 ength along the wide. The input im- ~ede~nce of the dielectric fil led guide is determined from the magnitude and Chase of the reflection coefficient by means of ° 47 _

s tending wave me~-ementse From these measurements, the nor- m~3 i red character' sty ~ Awe impedance of the diet ectric is ot- 1;~.ined from which the at~cenuetion and chase constants end in burrs e' and e,, or +~n A ~n be caucus specs.. A discussion of the t~a.namission ' ine theory and the e.~nro~ri~te ecuet'ons is given. Mee.surements at ~ Ire length of 33 cm. using this method are reported for paraffin ),r~9 d~ strene, e.nd ebonite Pond a.re com- n~rec! 'pith measurements by other investigators. Eesentie~1y the gaffe method an] technique seems to have been developed and need independently by Birkel~O for his measurements on the magnets c dispersion of iron oxides at centimeter weve_lengths, by the baiter for dielectric measurements at micro~^rave freauer~c'es during the firer (unpublished) end by Willis and Crouch274. As indicated in Section IT, Bevel papers dealing ~;n dielectric measurements at microwave frequencies were ~re- sented at the Bat timbre meeting of the Conference on Electrical 7~su~ ation. These included a reamer on Dielectric Constant and ~s Me~'tlrements from ~ to INTO cycles/sec. by vleatphal; Hero haters on Dielectric Measurements at Microwave Frequencies, one by Dakin and Works, and the other by Yager; a Hater on Modifi- cetion of the Resonent Cavity Method for Dielectric Measurements at ~ Fixed Frequency ty Beker5 end a. later on A Resonant Cavity Method for Dielectric Measurements at 300 me. by Muller, Leef and t.~.Ja~rner e Abstracts of there pulpers Bail ~ appear in the forth- coming Annual Report of the Conference on I:lectrica.1 Insulation. V ~ Frecuency Measurements A fear ~e~s dealing specifically filth frequency men appeared during 1946. A paper by Dexter 275 aims to give an overall picture of the nets frequency measurement requirements and to do scribe some of the special e~pr~aratus bei ng usecl. Tt includes ~ non-mathematical di scussion of Butterfly circuits and resonant cavities. A resume of the more conven- timing types of waverneters the t are used to measure u1~Gra-high- f~requencles is given by Endall 276. Inetruments are described +~$t make it possible to messmre freauencles in the Ah. f. and micro rare region up to 3000 mc. Tuned-circult absorption wa~re~netera covering the frequency range 100 to 800 cm., a variable capacitance any inductance '`ravemeter that is tunable within the range 150 to 800 me., a commercial ~r~iabl e ca~aci- tance and inductance wavemeter that is tunable within the range 55 to 400 me., a commercial wavemeter using a butterfly tuned circuit with a. turning range from 240 to 1200 me., a transmission ~ ine abeorn~Gi on wavemeter9 a Lecher Brace system, and a commerce al heterodyne frequency meter for measurements UT' to 3000 me. are described, Dickson 77 discusses the determination of very high frequencies, and Es Ben and ¢ordon_.Smith278 describe ~ reportable enDa~atus for frequency measurements in the range 100_10~000 me. in terms of a standard q,;:artz oscillator. Several papers cited in Section IT E2 also deal With frequency measurements. ~ ~8

Measurements An arts cle bye Clayton279 and others surveys the menthols and techniques used in the O.E.~. Research Laboratories. Magne_ irons and velocity_modulated tubes form convenient sources. Frequency measurements involve either heterodyne methods or re_ sonant circuits such as the cavity ',ravemeter, the latter being described in detail. Power may be measured by a bo~ometer or by an artificial good, lawns or strafer. Imnedance, voltage, current and field strength measurements are discussed. - Gaffney280 ore- sents a brief Summary of some of the more import=" measurements methods and discusses the electrical and mechanical considerations in the design of Tnicrowa~re measurement equipment. Accuracies obtainable trith the Present state of the art are given. . . Sprouts and Linder281 are concerned with resonant cavity measurements, using a cathode-ray oscilic~scope as indicator. The traced astern indicates the frequency response of- the cavity. . The limitation a and accuracy of the method are discussed. The Q is measured by reading the half-not`~rer points versus frequency deviation. The shunt resistance is defined as a voltage difference between two Points, divided by into times the power dissi~tecl. in the caviler. Methods of measuring this quantity are described. Other papers dealing with microwave measurements are listed below: Microstate Measurement _ Banks282 HighIt~ht;s of' High Frequency Measuring Technique \fehrlin 283. High-Frequency Mee.surernents - SinClair284. Micro'`,ave Test and Measuring Equipment - Cones 285. ,`.ra~reguid e Measurements _ Ashdown286. Scientists Retriever Progress in the measurement and Utilization of UHF Siennas ~ and Propagation Ch?~racterts~ic~2~37 ~ Meesurement of the Angle of Arri~re~ of vicro:ra~res Shern3.es~3238 Further Observations of the Angle of Arri~-a] of ',icro~re'.ves _ Cre''~ord and Sharps ess269. IV E. Anelysis of_ Cir~n~and Components In order to conserve spice the darers dealing huh the tonics of this section are merely lleted by title belong: _ 49

The Ge.~ ~re.nometer and the Bridge - Mlller290 Near Type of Electrostatic Generator - Miller29) Portable High-Voltage Cable Test Unit - Hui~chins292 Stabs 1 1 ted De C ~ High-Voltage Supply _ Gurewitsch and Noble 293. Trs.r`smit+ing High Currents on Eliding Contacts Antrim 294. Cherac4cerist;ice and Errors of Capacitors Used For Measurement Purposes _ Gerton295. ED ectrical Men. suring Ins~;rumen1;s - ockenden and Gal ~ 296. Hi~h_Pesistance D.C. Vol~met;er - WaiAelick297. . Electrometer Innut Circuits _ Thomas 298. Meter for High-Vol+~ge Measurement - Alfren and Eklund299. Inverse Vacuum Tube V£)1 tmeter _ Dike300 e Theoretical Study of the Use of ~ Thermocouple in Precisign veasurement of A.C. Power - Coffin and Marchal~°~. Test Osci] ~ actor _ Moore302. Frequency Meters as Master Osci1 lators _ Conklin505. Sirn`~le Square_W.eve Generator - Roadley304. bees of Souare-~.aves and How They May be Generated I~ebens305 . elide Range Test Oscillator _ A Generator Delivering; Sine _ or Square-Wave Output - Lober306. 135 to 500 me . Signal Generator - Won8 OWt C Z and Bri er307 . Coaxiel Butterfly Circuits - ~ro8~5o8. Oscillators ena A~n~llfiers at 100 me. Using Llght- house Tubes axld Cavity Resonators in the U.H.F. Region - Rand309. The Resnatron - Can Generate 50 KW Continuous Ware at Any Frequency Between 350 and 650 me. - Sa:Lisbury3~0 - 50

Blmnlified Bridge Analysis - Ml1-ler3ll. Production Bridge for Incremental Tests ~ I!Uller3~2. lied Radio ~ Frequency Bridge - Tiffany3~3. A Radio Frequency C3~a4clte~nce and Conductance Bridge Proctor and James . Ne,' Righ Frequency Bridge _ Whaley3~5. Equal Ratio Impedance Bridge - Alexander316. Phase Sensitive Bridge Detector - Hunt,er3~7. A Visual Mull Indicator for Impedance Bridge Measure_ meets at Radio-Frequencies - Brine and '.~itehead3~80 Bridged- Circuit - Essex319. Note og a Parallel_T Resistance-Ca~P-citance Network Wolf 20~- Theory and Application of Perallel-T Resistance- ~ Can~.citance Frequency Selective Networks _ Stanton32~. Analysis of ~ Resistance-Ca~acitance Paral~el_T Network and Applications - HaStinge322. Note on a Reflection_Coefficient Meter - Korman323. Radio-Frequency Spectrum Analyzers - Wi]1isms324 Theory of a Microwave Spectroscope _ ~a~25. Bridge for High-Resistance, Righ-Volte~e Measuremente Miller326. V. Bibliography of Some .~7ew and Improved Commercial Instruments For Electrical Testing . The following bibliography of some net and improved commercie! instruments for electrical testing is not a11-inclusive NO COULD there are many others which have not come to the ,witer's attention. It is included here primarily to give the reader a bird's eyebvie,~r of the nature end extent of deveJo~ment.s in the field. of commercial electrical teet equipment. Conductivity Cell - Positive Floss Type. Industrial Instruments' Inc e ~ Elec. Equip., 6, 7, den. (1946) Portable Instrument Checks Electric Insulation Resistance. Associated Research. Ind. Equip. Mews, 14, 2QS ~ct-~194~) - 51 _

Port Able Lumen Checks E1 ectric Insu] ation Resistance . Id en] tndllstri e s ~ Into Equip O .~7et~s, 14 ~ 59 ,, Beat . ~ l~46 Insulation Tester Designed to Test Insulatior~ frown ~ to 10,000 megohms at 500 Violas. Radio City Products Co., Into, Electronics, Ig., 230-2, Beat. (1946) Insulati on Tester _ Volta~e ~lariabJ e to ~ S kv. Lyman E1ectronic Oorc.; Elec. E:qui~. 6, 33, A~ri7 (1946) YJond,.action O~ri ~ Cur-fent FIego~meker. ~leston Engg. ~To~ces, l, l_2, Aor. (1946) 3ri ~ge ~ n strume n~ f or Te ~ ti ng Re g i ~ ~ or ~, C ondens er s, and ` nd.uctors. Freed Transformer Co. $ Ind. I:quin. News, ~4, 71, May (1946) 2e ] 261 Vibro_Test i s ~ Portable ana Entirel y Selt Corttsined Insulat. on Resistance Meter ~esting to ~ ~ ~ 000 Meg~hms . E3adi ~ News, Radi Q - Elec tr oni c Dent . _, 20, ]~ly ~ 1946 A Com~1 ete Llne of S~here Geps for the Accurate Measurement of Righ Voltages Used in D.C. or A.C. Testing. Gene Elec. Co. G.E. Rev., 4~3' 74, Nov. (1945) n A.~. Onerated Power Sun~ly for Instruments. Gen. Re di ~ E=er ., 20 , 4_6 , Mar . ~ 1946 ~ Me~F DUa] RegUTa~eJ POT~er SU~.Y. PG1~ad Ele-ctronics CO. InStrUmentS, 19, 364, JUne (1946) Z-Meter for Electrica~ and E:lectroacoustic Mee~surernente. Packard, L.E. ~ Electronic Inds., 5, 42-5, Dec. (1946) Whe?~:stone Bridge e Winsio,? Co.; Elec. Eauip., 6, 4, Ar)r. (1946) :.~1heatetone 3ridge. Wilson Co. Feb. ~ 1946 ~ Elec. WorId, 125, Il4, Mod el 406 Electronic Volt-Ohmmeter Feetures Ex~Greme Pan~e and a New Bridge Type circuit for Maximum Stabi lity and Accuracy. Cli~ard Instrument Lab.; Instre. 1 9, 22S, Arr e ( 1946 ) __ Mode~ 20~3 ie Desi~ned to Perform More Functions Than Most Volt-Ohm-Mi~ 4.iamme~Gere. It measures wide ranges of capacity, reelstance, a_c and d-c current and voltage. Inductarlce ~neasurements are a~ so nossib~ e e Hiskok Elec. Instr. Co.; Radio, 30, 44, A~re (Ig46) - 52

No. 3030 d-c volt_emmeter is a ~ortab~ e instrument from Rich 40 interchangeable ranges can be obtained Keith en accuracy of 0.5~ of ful l-ece~1 e deflection. Standard Science Supply Co.; Inetrs., 19, 228, Air. (1946) Sensitive r.f. voltmeter presents the principal Lea feature of greater band width, the high frequency limit being extended to beyond 5 me. Ballantine Lebore~cories. Rear. Sci. Instr., 17, 161-2, Apr. (1946) VT Von tmeter With 7" Meter. Precision Apparatus Co.; E] ec. Equip. 6, 32, Feb. (1946) A Vow tmeter Rich Extends the Range of Measurement Ten Tines - From 50 to 500 me. Alfred W. Psarber La.bora_ tories; Radio, 31, 24, ~Jan. (1947) Radio Frequency Voltmeter to Read Die J ectric Heating Potential . R.C.A.; Mona. Equip. Nests, 14, 30, Dec. (1946) Near Voltohmyst can be employed for high impedance circuit testing at frequencies un to 250 me. R.C.A. Electronic s, 19, 23S, Dec . ~ 1946 ~ Peak_Reac~ing Voltmeter for the U.H.F. Ranges. Gen. Radio Enter., 21, l_S, Oct. (1946) b High Frequency Voltmeter. Hewlett_Packard CO.; Electronics, 19, 208 Aug. ( 1946 ) Ne;' ''Model 424 Volt-Ohm-Milliammeter'l incorporates a 5~1 Syndical or ,~.Tith a sensitivity of 2500 ohms per volt and ~ Increment of 400 microamperes. Radio City Proclucts Co.; Instrs. 19, 286-7, May (1946) Electronic Voltmeter Peads 0.001 to 1 Volt in 3 Decade Ranges. Ballantine Laboratories; Ind. Equine Nears, 14, 32, June ~ 1946 ~ New ''Mooched 29" high-frequency probe is said to represent the firing practical answer to the Problem of measuring restages in very high-freo,uency circuits. Alfred W. Barber Laboratorl es. Instrs., 19, 277, May (1946) Type 650 Impedance Bridge. Den. Radi 0 Expel., 20, 1, Acre (1946) T?andy Pair of Bridges. Lameon, R.,J., Gen. Radio ExPer., 20, 3-7, Feb. ~ 1946 ~ Frequer~cy-Insensi4sive Rest store. Corning GIas~ Works . Electronic Inde., 5, 6S, Mar. (1946) - 53 -

Thermocouples for Making Measurements at Q.H.F. Field Electrical Instrument Co. ; Electronic Inde ., 5, ll2, ]~n~ ~946~ Thermocour'1e Ammeters for Very High Frequency. Weston Engg. Notea, I,, 7_S, Apr. (1946) UHF Signal Generator for General Laboratory Use. Fre- quency Range of 500 to ~ ,,350 me. Hew~et+_P7.ckard Co., Elec ~ World ~ 127 ~ 94, Feb O ~ 1947 ~ Aide Range URF Test Oscillator, Gen. Radio Exacter., 2l, 4~ ~ ~ ~Tov ~ ~ ~ 946 ~ New ''Ty~e SD-835- Fit Reflex Klystron Designed for Operate on at Slave ~ erigth$ Between 6 and 7 cm. Re- seareh Laboratories of Sylvania Electric Products, Ino.; Tsars., :l9' 299 May (1946) Inner precision_Buil~G, High_Leve', R.F', Signal Generator Covering the Range from 400 kco t;0 60 me. in Six Sheds. Barker and ,'[illiameon. Radio Nears, Radio_ Electronic Dect., 6' 26' Feb. (1946) Frequency Meter Covers Range from l.5 to 100 me.; Browning Laboratories, Inc.; Alec. Equip., 6,, 25, June ~ 1946 ~ 7~IF Wa~remeter Designed f or Rapid Measurements of Fre- quency in the Range 240 to 1200 me. Gen. Radio Co*, Elec. Equip., 6, 23, Feb. (1946~; E-lec+,ronics, 19, 302 ~ Jan. (1946 ~ Wave Guides Designed for EN ectrical Equipment. Amer. Bums Co.; E1ec. ,nrOrId, 1~5, 146, ITS, May (1946) Flexible ~laveguide Trademarked "lfavef~ex." Titef~ex, Inc ~ , Radio News, Radio_E1 ectronic Dent. , 6, 28-9, Air. t 1946 ) SIot4ced Measuring Line for Measurir~ Impedances at V.~.F.; Ferris Instr. Co.; Elec. Equip., 6, 24, May ~ ~ 946 ~ Micro~.~.ve Tnstruments. Sherry Gyroscope Co.; Radio, 30 44 ~ Febe ( 1 946 ~ Lightweight micro are event inch udes an oscillator and band intensity meter for study of practical ly El]_7 the Rowena or e] ectro~t~.gnetic redi ations at ultra- high frequency Get. Heart , 49, 50, July (1946) Tern Electra c Silicon arty Germanium Crys-~1 Pectin fierce R., 30,, 34., Mar. (1946)

Crystal Converter. Type lN21B silicon crystal 8 can be used as first detectors in high frequency sur~er- heterodyne receivers in the region of 3,000 me. SyIve~ia Elec. Products, Inc.; Electronics, 19, 22S, Oct. (1946) Field Indicator. Nell R.F. probe for testing high frequency po'''rer circuits. Radio Frequency Labora_ tories, Inc.; E]ect;ronics, 19, 226, Oct. (1946) Near Vacuum Type Bolometer for Une in URF Bridge Circuit Measuring Equipment. Lynn Engineering Co.; Electronic Ind., 5, ll2, Mar. 1946. Computation Aids Am. A fen' pacers have appeared ashore aim is to simplify and expedite the ce. Iculation of Sari ous quantities. GlinsM327 shows how high-freauency impedance matching network problems are sirn~li_ fled by ~ method based on circle diagrams. The graphical ca.]cu- lation of double stubs is considered by paine528 and a simplified method of ~l otting a~Gtenuati on curves is described by Biberman329. 6~ decibel conversion chart is given by Mie~ke330 and an impedance nomogram, by Wheeler331. Baine352 presents a universal chart f or unbalanc e bri dge 5 _ $ ~ -

BIBLIOGRAPHY Matllre , 158s , 121_4, July ~ 1946 ) 2. Engineering, 161, 571, June (1946) 3e Englneer, 781' 51~-20, June (1946) 4 Ind. and Eng. Chem., 39 , 1090_1129 , Nov. ( 1946 ) 5. Keng) B.P., Elec. Eng., Trans., 65, 403_7, July (1946) 5~3oG~ici:, Ee, J.A.C*S.,, 6a, 177_81, (1946) Gb.~=onick, E., J1. Phys. Che!L, 50, 291-300, July (1946) 7. Jones, ]. H., J.An~.Chem.Soc., 6S, 240-1, Feb. (1946) 9. Ralston, A.W. and FIoerr, C. W., J. Am. Chem. Soc., 68, 2460_4, Dec . ~ 1946 ) g. Field, P. F* ~ J1. A~11 ed Phys ., 17 , 318_25 , May ( 19466 ) 10. Chandbury, S. tI., JI. }'hys. Che=, 50, 477_85, Nov. (1946) 31. Fox., F. E. and others., Phys. P.e~r., 70, 329-39, Sect. (1~46) 12. Og~, R. A., Jr ., J. A~n. Chern. Soc ., 6a , 15 5 ~ 1946 ) 13. Ogg, R. A. Jr., Phys. Rev., ~, 668-9, June (-1946) 14. WeisPman, S. I., Phys. Rev., 70, 571-2, Oct. (1946) 15. Mushran, S. P. and Prakash> S., J1. Phys. Chem., 50, 251_6, May ~ 1946 ) 16. Ka.ls.bukhov, N., J1. Phys. U.~.~.R., 10, 61_3, (1946) 17. Busch, G., Helv. Ph:YS. Act~a, 19, 167-fJ8, 189_98, 463_92 (1946) 13. Morton, P. L., Phys. Re~r., 70, 358_66, Sept. (1946) 19. Margeneu, R., Phys. 3Pev. 69, 508-13, Me.y (1946) 2~3. Smith, A. W. and nther8, J1. Anplied Phys., 17, 33_69 Jan . ~ 1946 ~ 21. Pi~r)ar], A. B., Nature, 158, 234_5, Aug. (1946) 22. Partington, J. R., Nature 1bS, 835_6, lDec. (1946) - 56 _

23. Field, R. F., Phys. Rev., 69, 688 (1946) 24. Dmitriev, V. A. and Gure~rich, J. B. J1. Ex. Th. Phys., U.~.S.R., 16, No. 11, 937-40, (19463 Snoek, J. L. and Pre, F. R. der, Philips Tech. Rev., 8, 57_64, Feb. (1946) 26. Rector, L. G. and Woernley, D. L., Phys. Rev., 69, 101_5, Feb. ( 1946 ) 27. Albright, 1?. S. and Costing, L. J., J. Am. Chem. 8oc. 68, 1061_3, ~ 1946 ) 28. Dakotan, O.EC., J1. Phys. U.~.~.R., 10, 183_90 tl946) 29. Cooper, R. J. Inst. Elect. Eng., 93, pt. III, 69_75, Mar. ( 1946 ~ 30. Schallamach, A., Trans. Faraday Soc., 42, 495-507, (1946) 31. Oster, G., J. Am. Chem. Soc., 68, 2036-41, Oct. (1946) 32. Mater, W., Phys. Zeits., 45, 285-97, Mar. (1945) Wearers, M., Philips Real P.eporta, 1, 197-224, 279-313, 361_79, 447_64 ( 1946 ) 34. StAger, R. and others, Sch~reiz. Arch., 12, 372-90, Dec. ( 1946 ) 35. Fr~hlich, H., Roy. Soc. Lond., Proc., 185, 399_~14, Air. ( 1946 ) 36. Balls, W. L., Nature, 158, 9-11, July (1946) 37. Electrical World, 125, 126, Feb. (1946) 39. Schallamach, A., Nature 158, 619, (1946) 39. Mason, W. P. ~ Phys. Rev., 69, 173_94 (1946); Bell Lab. P.ecord, 24, 257_60, July (1946) 40. Mason, W. P., Phys. Reve, 70, 529-37, Oct. (1946) 41. FTaviaa J L. and Green, R. L., Am. Cer. Soc ., J1., 267_ 76 ~ 19.46 ~ 42. von Hillel, A., Breckenridge, R. G., Chesley, F. A. arid Tisza, L., Ind. and Eng. Chem., AS, 1097_1109 (19463 43. He Britte~ri:Lle, A., Jr., Am. Cer. Soc., J~ ., 29, 303-7, Nov. ~ 1946 ~ ; Bull. Atn. Phys. Soc . , 2l, TO-9 (~46 ~ ; Phys Rear., 69, 689 (1946)

44~ Wllig B. M~ ~ t`~ature$ 1573 808, Jlme (1946); J1. Phye. ll.S.~.R., :LO,, ~Q. 1, 64_6 (1946) a.nd No. 2, 95_106 (1946) Wul, B. M. e.na GoldrQan, I. M., Acad. Sci. J U.8.~.R., 5l, ~1~3 ( 194& ~ ^5,, l`Jul, B. M. and Ve~esche.genl L. F., Acad. Scio, U*~.S.R. , 48 , 63~ ~ 1946 ) 46. Je.ck8Or~8 W., erld Red lsh, W., Ne~ture, 156, 717, Dec. (1945) ^7. Coursey, P. R. and Brand, K. G., Nature, 157., 297_8, M~rch ~ 1946 ) 48. Baller,, E., Cahiers Physe, 20, 1-20 (1944) 49~ Luttinger, J. ~e and Ti~za, Le ) Phys. Re~r., 70, 954-64, Dec 4 ~ 1946 ) 5&. Bbt-~her, C. Je F., Rec. Tra~r. Chim.; 64, 360_2 (1945); 65, gi-g (194&) 51. Miller, A. R., Cambridge Phil. Soc., Proc., 42, 292-303, Oc ~ O ~ 1946 ) 4 lIannay, N. B ~ and Smyth ~ C. P. , J. Ame Chem. Soc . , 68, 171_3 ~ Feb . ( 1946 ) 53 * Hannag, N. B. end f3myth, C . 244_7, Feb. ( 1946 ) P., J. Am. Chem. Soc., 68, 54. Xannay, N. B. and Smyth, C. I?., J. Am. Chem. Soc., 68, 1005_R, June ( 1946) 55. lI~nnay, N. B . and Smyth ~ C . P. , J e A.m. Chem. Soc . , 68, 1357_60, July t 1946 ) 56. P"ogers, M. T. and Young, A., JO Am. Chem. Soc., 68., 2748, D~c . ( 1946 ) 57. Sauer, R. 0. and Mead, D. J., J' Am. Chem. f30c., 68, 179407 Sert. (1946) 58. Hll~ er, J. G. and Angel ~ H. ~ ~ ,, J. Am. Chem. 80c. , 68, 2359_9, Nov. ( 1946 ) 59. Gent, W. L. (~., Nature, 158, 27, July (1946) 60. Ste~anenko s N. and Agranat ) V., J1. Ex. Th. Phys. U. S. S.R. 16, No. 6, 537_42 ( 1946 ) (il. Stecenenko, N. and NcYikova, T., Act. Phye. Chim., U.S.~.R. 9 20, 6S3_66 ( 1945 ) __ ~ 62. S~lnr~.d, B. I. ~ Je Ame Ch~mO SOc. ~ 68, 617-2O, Apr. (1946) _ 58 -

63. Rogers, M. T. and Roberts, J. D. , J. Am. Chem. Soc . , 6S, 843_6, May t 1946 ) 64. De.ViS, R., J. Inst. Elect. Eng., 93, fit. 1, 177_86, Air. (7946) 65. Meek, J. M., J. Inst. Elect Eng., 93, it. II, 97_110j disc. 110_5, Air. (1946) 66. Posin, D. Q., Phys. Rev., Be, 541, May (1946) 67. Thonemax~n, P. C., Nature, 158, 61, July (1946) 68. Browns, T. E. ~ Jr. , Elec. Eng., Trans., 65, 169_76, Mar. (1946) 69. Mikuradse A. and Berger, A., Phye. Zeite., 45, 71_81, May ( 1944 ~ 70. Seeger, R. J., Acad. Sci., J1., 36, 2~5_93, Sept, (1946) 710 Adams D. O., Parer Trade J1., 122, 43_52 (lg46) 72. Ruto'o, A. and. Padres, B:. E., Am. Soc. Testing Materials Bull., No. 142, 34-7, Oct. (1946) 73. Austen, A. F:. W. and Pelzer, H., 3. Inst. Elect. Eng., IS, LOG. ], 525-32, Nov. (1946) 740 Davidson, J. W., Physe Peer., 70, 685_9~3, Nov. (1946) 75. Bright, E. G., Elec. Rev., Lond., IDS, 733-6, May (1946) 76. Hill, J. E., vrestinghou.se Engr., 6, 134_45), Sent. (1946) 77. Andes, C. L., Am. J1. Phase, 14, 379_82 (1946) 78. Sister, J. C., Revs. Mod Phys., 18, 441_512, Oct. (1946) 7~. Feenberg, E., J1. Applied Whys., 17, 530-2, June (1946) 80. Miles, J. W., Inst. Radio Eng., Proc., 34, 728_42, Oct. (1946) 81. Electronics, 1~3' 222, Oct. (1~46) Q,2. Travlson, R., Radio Me,.~.rs, Radio_Electronic Dent. , 6, No. 1, 15-R, 20, Jan., (1946) 83. Bolero, T., EJ ectronics, 19, 99_103, Mey (1946) Be=. Seeley, S. ,+Elec. Mfg., 37, 102_5, 180, Mar. tl946), 128-31, 192 ~ Air. ~ 1946 ) P5. O-linski ~ 3. , Elec ~ Eng. ~ Trans . , 65, 46_9, Feb. ( 1946 ) 59 _

P.6. th'l~i~s, E. N. , Electronics, 19, 137_9, Jan. (1546) 87 ~ &~3 ker,, L. R. and ~A.'ax. M. 5 J1. A~1 fed Phys ~ , 17 ~ ~ 043 ~5 Dec. (1946) 98. Cl~'rier, A. G.) E1ec. Comm., 23, 436-44, Dec. (1946) 89. Kem~ ~ J. , Wire~ es ~ Engr ~ , 23, 211 -6, Au~. ( 1°46 ) °~. Pekeris, C. L., J~. A~p~ied Phye., 17, 678_~, Aug. (~946) ~'~. Sa~uel, A. L., Bell Sys. ~ech. J1., 24, .~20 52. (1945) 92. Clarke, J. L., Bell Sys. Tech. J1 ., 25, 156_? (1~46) °3. ~'hi~e, G., R~dio Ne~rs, Radio-Electr-onic Delst., 6, No. 2, 5- 8 , Feb . ( 1946 ) 94* Fo~d, L. FI~ end. Cliver, R. , Phys. Soc. Lond., Proc. J 58 265-8O, ( 1946 ) 950 Lamont) H. R. L. and. ~.ratsorl' A, G. D. ~ Nature, 158, 943-49 Dec. (1946) 96. .~4uel~er, 3. E., Inst. Radif3 Eng., Proc., 34, 181P-183P, A~r. ~ 1946 ~ g7. Robertson, S. D. and King A.P., Inst. Radio Eng. ~ Proc. 34, 178P_~SOP, A~r. (19465 Q~ . `~,olo`~ , N . N ., J~ . Ex. Th. Phys ., U . S . ~ .R., 16 , N o. ll, g96_9 ~ ~ 946 ~ 99 ~ Rozovsky, M. ~ ., ]l o Ex. Th. Phys . U . ~ . ~ . R., 16 , No . 10 , 956_69 ( 1946 ) 100. Thor~ann, P. C. and King, R. B., Nature, 15S, 414, Se~t. ( ~ Q46) 101. Kelliher, M. 3. end. l`.relton, E. T. S., ~flirelese Engr., 23, 46-51, Feb . ( 1946 ) ].02. ktoreno, T., Electronice, 19, ]36_4l, 3une (1946) ~''<5. 7~ralter, ~. and othe~s, R.C.A. Rev., 7, 622~33, Dec. ~1946 7 04. Fiske, '~r. D ., Rev . Sci . Instr., 17, 47~83, No~r. ~1946 ~ 1 05 e Al lanson, J . T . n.nd ot;hers, J. Inst . E1 ect . Eng., 93; ~t e TI: , 177_87, -~ay ~ 1946 ~ 106. T an~b, I., ]. Inst. E:Lec~s. Eng., 93, ct. ITI, 18~3-90, May (1946) _ 6~) -

07. Winchell, A. Nov. ( 1946 ~ 08. And.ers ~n, A. Aug. ~ ~ 946 ~ 09. Rill, A. G. Rac i 0 Ne'.rs, Radio-Elec t;ronic De~JG ., 6, 3_6, 30-3, Mar. t1946) 110. Scaf~, ~J. E. e~nd OhI, R. S., Be]1 Bys. Tech. J1., 26, 1_30, Jen. ( 1947 ) 111. He.esel, F. and. Jenks, F., Electronics, 19, 134_8, Ms.r. (1946) 112 . F i sk ~ J e B . , Hags bum, H . D . J ~ nd Hartman, P ~ ~ . ~ Bel 1 Sys . Tech. J1. ~ 25 ., 167_34P, A}'r. ~ 19~ 6 ) 113 ~ Fle.nder ~, L. j Jr . ) Radio News, Radio~Electr onic De~t e ) 6 15_8, 20, 37_9, Mar. (1946 ) 114. ~ende;ll, J. T. ) Phys. Soc. Lond., Proc., 58) 247_52, lIay (1946) 115. Johnson, J. C. Western Electric Oscillator, No. 4., 7_10, 40, July (19463 136. Coltman, J. W., Ilrestinghouse Engr., 6, 172_5, Nov. (1946) 117. Lathem ~ R. and others, Englneer, ~a1, 31002, 331_3, Apr. ( 1946 ) 118. W~ll, T. F. ) Eng., 161, 125-7, Feb. 8; 148, Feb. 15; 1 84_5, Feb. 22, ~ 1946 ~ 119.-Coeterier, F., Philips Tech. P~ev., 8, 257_66, SeT't. (1946) 120. Lafferty, J. '4., J1. Apnlied ]?hys., 17, 1061_6, Dec. (1946) 121. Fogel, J. and Branae S., J1. Ex. Th. Phys., U.~.S.R,, 16, No. 2, 187_92, (1946 j 122. Round, R. lt., Pev. Sci. Instr., 17, 490-505, Nov. (1946) 123. 124. 125. 126. M. , CQ (Rndio Ame.teurs ~J1. ) , 2, 25-7 ~ 59-60 , R. and Winchell, A. M0, Electronics, 19, 104_9, Salisbury, ~r. w., Communicatlona, 26, 33, 49, June (1946) Se.lisbury, W. W., E7ectronics, 19, 9~7, Feb. (1946) I.aw, R . R. and others , R . ~ . A. Rev ., 7 , 253-64, June ( 1946 ) CI ark, Je W. and Samue1, A. L. ~ Inst . Radi ~ Eng., Proc 35, Sl_; Jan. (~947~ 127. Gure~ritsch, A. M., Electronics, 19, 135-7, Feb. (1946) - 61 _

128. Electronlcs, 19, 90_2, Non. (1946) 129. Eom~fner, R., Wireless World, 52, 369-72, Nov. (1946) 130. Malter L. and Molt ~ J. L., R.C.A. Rev., 7, 414_21, Sent . ~ 1946 ) 131. lerovax, 18, 1_3, June; 1_3, July (1946) 132. Motz, H., J. Inst. Elect. Eng., 93, pt. III, 335-43, Sent. (1946) 133. Mayer, E., J1. A=lied Phys., 17, 1046_55, Dec. (1946) Ludi, F., lIelv. Phys. Acta, 7 7, No. 6, 429-36, (1944) Lindern, Ce ~e von and Vries G. de, Philips Tech. Rev., 8, 149-50, May ( 1946 ) 136. Nicolae, P., Ann. de Radio-elec., 1, 181_90, Jan. (1946) 137. Giacoletto, L. J., Electronic Ind., 5, 6~2, Aug. (1946) 139. Guarrera, J. J., Electronic Ind., 5, 80_2, 120_2, Mar. (1946) 1.~. Wilson, I. G. and others, Bell Sy8. Tech. J1., 25, 408-34, July ( 1946 ) 140. Green, E. I., Fisher, H. J., and Felon, J. G., Bell E;y8. Tech. Jle 1 25, 4.55-82, July (1946) 141 o 13rc)dski V. B. But 1. Acad. Sci ., U. S. S.R., Ser. Phys . 10, No. 1, i7-22, t1946); ~780 SC1. Abs. B. id, 350, Dec. 16) 142. Harries, J. H. o., Electronics, 19, 132-5, Dec. (1946) 143. Jones ~ W. J., Radio, 30, 29-34, Jan. (19463 144. Banner, J., Electronics Eng., 18, 268_9, Bent. (1946) lab. McQuay, J., Radio News, 35, 36-7, 74-78, Feb. (1946) 146. Peake, H. JO, Radio$ 30, 13_5, Nov. (1946) 147. Eaten, L., Wireless Engr., 23, 126_32, May (1946) 148. Rand, P. S., QST, 30, 34_40, Apr. (1946) 149. Bard, R. E. , Radio Nears, Redio_Electronlc Dept., 7, 10_11, Sl, Dec . ~ 1946) 350. Quarles, L. R.,, Communications, 26, 20, 22, 24+, July (1946) 1-57 . Quarles, L. R., Conumunlcatlone, 26, 229 Mey (1946) _ 62 -

152. Crosby, D. R. and Pennynacker, C. H., Inet. Radio Eng., Proc. 34, 62P_66P, Feb . ( lg46 ~ 153. Ricl£in, E. M., Wireless Engr., 23, 308-13, Nov. (1946) 154. Early H. C., Inst. Padio Eng., Proc., 34, 803_7, Oct., (19465 155. Beggs, J. E. Electronics, 19, 204, 206, 208 , June ( 1946 ) 156. Feiker, 3. E., General Electric Rev., 49, 43_6, Sept. (1946) 157. Altar, W. and others, Inst. Radio Eng., Proc., 34, 33P-44P, Jan. ( 1946 ) 158. Early, H. C., Inst. Radio Eng., Proc., 34, 883-6, Nov. (1946) 159. Sci. News Letter, 49, 295, May (19~6) 160. 161. Van Fleck, J. H. , Phys. Rev., 69, 676, (1946) Van Vleck, J. H. and Weiaskoff, V. F., Rears. Mod. Phys., 17, 227_36 (1945} 162. Foley, H. M., Phys. Rev., 69, 616_28 (1946) 163. Raines, R. M. King, O. W., and Cross, P. C., Phys. Rev. 70, 108 (19465 164. Becker G. E., and Autler, S. H., Phys. Rev., Sent. ~ 1946 ) Autler, S. H., Becker, G. E. and Kellogg, J. M. B., Phys. Rear. 69 t 694 ( 1946 ) 165. Kyhl, R. L., Dicke, R. H. and Beringer, R., Phys. Rev., 69, 694 tl946) Dlcke, R. H. , Beringer R. , Kyhl, R. L. find Vane, A. B. , Phys . Rev . , 70, Sent. t 1946 ) 166. Dicke, R. H., Rev. Sci. Instr., 17, 268_75, July (1946) ·67. To,vnes, C. FI. and Merritt, F. R., Phys. Rev., 70, 558-9, Oct. ( 1946) 168. Beringer, R., Phys. Rev., 70, 53-7, Jul.- (1946) 169. lIershterger ~ tl. D. , `.J1. Applied Whys. ) 17, 4~5_500, June ( 1946 ) Walter, J e E. arid Her.shterger, W. D 7, 814-22, Oct. (1946) _ 63 - 70, 300_ 7 , J1. Applied Phys.,

Rershterger, W. Do and others, B.C.A. Rev.,, 7, 42~31, Sent O tl946) 170. Sweeney, B. and Penrose, R. P., Nature, 1579 339 (19~6) 171. Townes, C. H. 9 Phys. Rev., 70, 66.~_71, Nov. (1946) 172. Good, W. E. ~ Phye. Rev. ~ 70, 213, (1946) Hadley, L, N. and Dennison, D. M., Phy6. Rev., 70, 7~30_1, Nov. ( 1946 ) Doles D. A. ~ and Good,, W. E. ~ Phys. Rev. ~ 70, 9799 Dec. ~ 1946 5 175. Dailey> Be P. and others, Phys. Rev., 70, ABE, Dec. (1946) 176~ Dakin,, T. W. , Goods WO E. ) and Coles g D. K. ,, Phys. Rev. s 70 560 tl946) _, 770 Tomes, C. H. Holden, A. N. and Merritt, F. R., Phy6. Rev., 71, 645 Jan. t1947) 17Se Allanson, J. T. 9 J. Inst. Elect. Eng. , 92, pt. A- 3 247~55 Dec. (1945) 179. lElttel, C. J Phye. Rev. ~ 70, 281_90, Sent. (1946) 180. 13lr3~e, J. Bo, Nature, 15B, 671-2, Nov. (1946) 181. Purcell, E. M. and others , Phys . Rev . , 69, 37-8, Jan . ( 1946 ) 189?o Torrey, R. C. Purcell, E. M. and Pound, R. V. g Phyo, Rev., _, 680 ( 1946 ~ Pound, R. V., Purcell, E. M. and Torrey, H. C., Phys. Rer. , 69,, 681 ( 1946 ) 1~35 . Purcell , E. M. and others . Phys . Rev., 70, 986-7, Dee . ( 1C46 lS4 . Purcell, E. M. and others. Whys. Rev., 70, 98S, Dec. (1946) 185. Block F. ,, Hansen,, W. W. and Packard, M., Phys. Rev. ~ 69 127' ~lg46~; 680 (1946) BloCk9 ~e 9 Ph`8o Rev. 9 70, 460_474 (1946) block, Fo, EIaIl63eng Wo W. and Packard, M., Phys. Rev., 70 47~485 ( 1946 ~ ~ 186 . Frenkel, J ., J. PHYB ., U. S. S .R., 9, No. 4, 299_304 ( 1945 ) 187. ~avoisky5 E. ~ J. Phys.,, U.S.S.~., 10, 170_3 (1946) _ 64 -

187~.deVri jer F. W., Volger, J. and Gorter, C. J., Physica, 11, 41~8 (1946) 188. Griffiths, J. lI. E., Nature, 158, 670-1, Nov. (lg46) 189. Rittel, G., Phys. Rev., 71, 270-1, Peb. 15 (1947) 190. TIughes, R. K., Phys. Rev., 70, 570_1, Oct. (1946) 191. Maddock, A. J., J. Sci. Instr., 23, 165_73, Aug. (1946) 192. Winlund, E. S., Elec. World, 126; 80, Aug. 3; 98, Aug. 17; 84, Aug. 31 (1946 ) 193. Bock, A. P., Electronics, 20, 126, Jan. (1947) 194. Osborn, H. B., Jr., Elec. Contracting, 45, 81_4, 86, 88, Jan. (1946); 113_6, 118, 120, Feb. (194~ 195. lIartshorn, L., Mature, 157, 607-10, May (1946' l9B. Cable J. W. j Elec. Contracting, 45, 97-100, 102, 104, 108, Mar. ~ 1946 ) 197. Tinnerholm, A. R., Mod. Plastics, 23, 180_2, Air. (1946) 198. Nielson, R. A., Steel, ;~, 102, 104, 106, 112, Mar. (1946) 199. Bosomworth, 9. P., Rubber Age, 59, 429_40, July (1946) 200. Roberds, W. M., Inst. Radio Eng. , Proc., 34, 489_500, July 201. Relfel, lI., Elec. Mfg., 38, 148, 150, 212, Oct. (1946) 202. Kleinberger, R. C., Electronic Ind., 5, 78-9, June tl946) 203. Eohler, F., Plastics, 5, 50, 52, 55, 91_3, Dec. (1946) 20~. Chimer, E. 1~., Elec. World, 126, ale, 102, Oct. (19~;6) 205. Seeley, W. C., Elec florid, 126, 88_9, July (1946) 206. F5ro:m, G. H. end others, Inst. Radio Eng., Proc.. t',TeveS anti Electrons, 1, 5871-65W, Feb. (1946) 207. Schutz, P. W. end Mcvehon, E. K., Ind. and Eng. Chem., 38, 17~_84 t Peb. ( 1946 ) 208. WinJund, E. S., Electronics, 19' 108 (1946) 209. Electrician, 136, 351_4, Feb. 8, (1946) 210. E1ectronice, 19t 170_2, 174+,, Mar. (1946) _ 65 -

211. Ind. Equin . Ne: rs, 14, 1, Peb. ( 1946 ) 212. Purchasing, ~2, 180, 184, Me=. (19*6) 213. Ind. E('ulpe News ~ 14 ~ 24 ~ Feb. ~ 1946 ) 214. Mittelmar~n, E. and Bo~omworth, G. P., Electronics, 19, 128-30, Mar . ~ 1946 ~ 215 . E1 ect. West, 96, 59_60, Jan . ( 1946 ) 216. Eng. File Facts, Matls. And Methods, 23, 183, Jan. (1946) 217. Brumle~re, C. C. J Plastics (pond. ) 10, 7_10, 56, Jan. (lg46) 218. Smithera, V. L., India Pubber World, 113, 505-7, 566, Jan. t 1946) 219. Electronlc Ind ., 5 , 84_5 , Jan. ( 1946 ) 220. Elec. World, 125, 126, 128, May (1946) 221. Tel~nisk Tidekrlft, 75, 1087-99, Octe (1945 ) 222. Cole, H. 1~., Elec. World, 125, 102-3, June (1946) 223. Textile Worlcl, 96, 118_21, 212, 217 , May (1946) 224 ~ Ind. Equip ~ Neons , 14, 1, 105 , June ( 1946 ) 225. 226 ~ 227. 228. 229. 230. 231. 232. 233. 234. 235 236. SCI. Am. 3 174, 157, Apr. (1946) Electronic Ind., 5, 92, Feb. (1946) Elec. West, 96, 61, June (1946) Stirneon, T. E., Jr. , Pop. Mech. 85, 108_15, Apr. (1946) Ind. Equip. News, 14, 99, Mar. (1946) Ind. Equip. News 9 14, 80, Aug. ( 1946 ) Rambo, S. I., Electronics, 19, 120-2, Air. (19*6) Metallurgla, 34, 210_2, Aug. '1946) Electronic Ind., 5, 62~3, Non. (1946) Grsham, R. C., Racho Nears, 36, 46_S, 155+, Oct. (1946) Darner, A. J., Waves and Electrons, 1, W51-W37, Jan. (1946) Earner, A. J., Elec. Communication, 23, 63_9, Mar. (1946) 66

237. Krueger, R. M. and Raabe, C. A. - Plastics, 5, 26-7, 99-100, Oct. (1946) 238. Krueger, R. M., Q8T, 30, 51_3, Air. (1946) 239. Smith, E. W., Wireless World, 52, 129-31, Apr. tl946) 240. Johnson) Ee 0e ~ R.,C.A. Rears, 7) 272-80, June (1946) 241. Zinmerman, K., Radio, 30, 13-5, May (1946); 20_1, 32, 55_6, June ~ 194.6 ~ Zimmerman, E., ED ec. World, 126, 102, Nov. (1946) 242. Cox, C. R., Electronics, hi, 130-5, May (1946) 243 . Ind . Equip. News , 14, 22, Ardor. ~ 1946 ~ 244. Cragg.s, J. W. and Ranter, O. J., Quart. Apt. Math., 3, 330-3, Jan. ~ 1946 ~ 245. Kal~mann, H. E., Inst. Radio Eng. , Proc., 34, 348-51, June ~ 1946 ~ 246. Electronics, 19, 330, Jan. (1946) 247. Mlldner, Re C ~ ~ J. Inst. Elect. Eng. , 93, At ~ III , 296_304 (1946) 248. Sampson, F. F., Jr., Wire and Wire Prods., 21, 885_8, 910_1, Mov. (1946) 249. Rer~logle, D. E., Electronic Ind., 5, 94.6, Air. (1946) 250. Elec . Mfg., 37, 158 , Jan. ( 1946 ) 251. Frey, lI. A., Distribution, 8, 10_1, Oct. (1946) 252. Litt, S., Radio News, 35, 44_6, 13.~_5, Jan. (1946) 253. Hutchins, L. H., Jr., Elec. World, 126, 64_5, July (1946) .. 254. Dexter, G., Radi o News , 35, 80, Mar. ~ 1946 ) ~ 255. Polgreen, G. R. and Tomlin, G. M., Electronic Eng., lS, 10~5, Ar)r. (1946) 256. Electronic Ink., 5, 76-7, Mar. (1946) 257. Mohler, J. B. and Sternisha, J., Meta1 Finishing, 44, 5Oo62, 99_100, Feb. (1946) 258. Pike, C. H., E]ec. Rev., Lond., INS, 11_2, Jan. ~ (1946) _ 67 -

?59. Vissers, W., Jr., Radio, 30, 23-4, 61_2, Jan. (1946) ~60. Hutchins, L. R., Jr., Elec. World, 126, 55_6, Oct. 26 (1946) ~61. Rosen, A., J. Inst. Elect. Eng. (Lond.) 93, pt. II, 383_6, Aug. tl946) 262. Stamford, N. O. and O.uarmby, R. B., Wireless Engr., 23, 2°5_8 ,, Hoer. ~ 1946 ) ~53. Kramer, 3. and Stolte, F., Electronics, 19, 128-9, July (1946) ~64. Thilenkov, I., J1. Ex. Th. Phys. U.S.S.R., 16, No. 9, 770-5, f 1946 ) We~ngagard, A. P. end Hazen, T. Preprint 90-11, Electroche~n. Soc. a Inc. ?66. Knol, K. S. and Strutt, M. J. 0., Physica, 9, 577-90, June ~ 1942 ~ 267* }Io~weegen, J. M. Fan, Philips Tech. Rev. 8, 16_24, Jan. (1946) 268 . Ro~!eegen, J. M. yen, Philips Tech. Peg., 8 , 278-86, Sept . tl946) 26g. Malov N., J1. Ex. Th. Phys., U.~.~.R., 16, No. 7, 607-13, ( 19465 270. Homer, F. end other=, J. Inst. Elect. Eng. (Lond. ), 93, pt. 3, 53_68 ~ Jan. (Ig46) 271. Reclean, BY. R., JI. Applied Phys., 17, 558_66, July (1946) 272. Roberts, S. and van lintel, A., J1. Applied Phya., 17, 610-6, Jut y ~ 1946 ~ 273. Williams, G. and Bolt on, H. C., Phil. flag. , 36, 862-73, Dec. (1945) 274. Willis, C.H. and Crouch, G.E., Princeton University Plastics Lab.., Signal Corns. Project, Report No. 5, P. 325-347, Air. ( 1947 ) 275. Dexter, G., Radio Nears, 35, 3~4, 110, 112, 114, Jan. (1946) 276. Endall, R., Radio Ne~ra, 35, 50_2, 94 , Sent. (1946) 277. Dickson, F., Inst. Radio Eng. (Aust.), Proc., 7, 20, July ( 1946 ) 278. Essen, L. end Gordon-Smith, A. C., J. Inst. Elect. Eng. (Lond. 92, At . 3, 291_5, Dee e ( 1945 ) _ 68 -

279. Clayton, R. J. and others, J. Inst. Elect. Eng. (Lond.), 93, pt. 3, 97_117; disc., 117_25, March (1946) 280. Gaffney, F. J., Inst. Radio Eng. , Proc., 34, 775_93, Oct. (1946 ~ 281. ST'roull, R. L. and Llnder, E. G., Inet. Radio Eng., Proc., 34, 305_12, May (1946) 282. Banks , F. F . , Jr. , Radio News, Radio-Electronic Dent. , 7, 7_10, 25 ~ July (1946) 283. ~Jehrlin, H., ABS. Suisse Elect. Bull., 36, 445_53, Jelly 25, (1946) 284. Sinclair, D. B., Radio News, Radio-Electronic Dept., 5, 14, Dec. (1945); 6, 11_4, 32_6, Jan. (1946) 285. Jones, W. T., Electronic Ind., 5, 48_54, 135_6, Nov. (1946) 286. Ashdown, O., Electronic Eng., ~a, 318_9, Oct. (1946) 287. Electronic Ind., 5, 75_7, 96, July (1946) 288. Sharnless, t1. M., Inst. Radio Eng., Proc., 34, 837_45, ItOY. (1946) 289. Crawford, A. B. and Shernless, W. M., Inat. Radio Eng., Proc., 34, 845_8, NOV. ( 1946 ) 290. Miller, J. H. , Weston Eng. Notes ~ I, 2-3, Feb. ( 1946 ) 291. Miller, P. H., Jr., Phys. Rev., 69, 666, June (1946) 292. Hutchins, L. H., Jr., Elec. World, 126, 114, OCt. 12 ( 1946 ) 293. Gusewitach, A. M. and Noble, P. C., General Electric Rev., 48, 46_52, Dee. (1945) 294. Anthill, M. B., Iron and Steel Engr., 23, 108_9, Sept. (1946) 295. GarIOn, C. G., J. Inst. Elect. Eng., (Lond.), 93, fit. IT, 398-408 9 OC t . ( 1946 ) 206. Oc!~enden' F. E. J. and Gal 1, D. C. s J. Ins~G. Elect. Eng. (Long. ), 93, pt. I, 343-54, hag. (19463 297. WaiJe1iCh, D. L., E1eCtrOnICO, 19, 158_60, Mar. (1946) 298 . Thome s, R . A., Elec tronic s, 19 , 130- 1 , D ec . ( 1946 3 2~9. Airmen, H. and Eklund' S., Rev. Sci. Instr., 17, 353_6, Oc t. (1946) _ 69 -

300. Dike, S. H., Electroni cs, 19, 140, 142, Aug. (1946) 301. Goffi n, G. and Marchal G., Ase. Suisse Elect. Bull. 37, 595_600, Oct. 5, (1946) 302. Moore, D. - W., Jr., Radio News, 35, 32_4, 68, May (1946) 303. Conklin, E. H., QST, 30, 34_5, 130, 132, Aug. (1946) 304. Hoa.dley, J. C., Radio News, 36, J=8-9, 161_3, Dec. tl946) 305. Lebena, J. C., Jr., Elec. Mfg., IS, 13~5, 1B6+, Aug. tl946) 306. Lober, C. F., Q8T, 30, 40-2, May (1946) 307. Wonsowicz, J. and Brler, H. S., Radio News, 35, 35_7, 114, 116,, Jan ~ ( lg46 ) 308. Pros a, E . E. Jr., Electronics , 19, I56_60, Apr. ( 1946 ) 309. Rand, P. S. ', COST, 30, 34-40, Air. (1946) 310. S&]lsbury, W. W., Electronics, Ad, 92_7, Feb. (1946) 511. Mill er, J . H . , We £ ton Eng. Notes , I, 7-8, June ( 1946 ) 312. Muller,, W., Electronic Ind., 5$ 7~3, ITS, 120, 122, May ( 1946 ) 513. ~lffany, J. M. Western Electric Oscillator, No. 4, 36_7, 42, July (19465 314. Proctor, R. F. and James, E. G., J. Inst. Elect. Eng. (Lond.) Ha, At. 3, 287-90, Dec. (1945) 315. Haley, H. R., Western Electric Oscillator, No. 5, 30-2, Oct. (1946) 316. Alexander, L. G., Amalgamated Wireless Assoc. Techn Rev., 7, No . 1, 59-77 ~ ( 1946 ) 317. Hunter, P. H., Electronlc Ind., 5, 60_~., June (lg46) 318. Brine, P. J. and ,1hitehead, J. W., Rev. Sci. Ins tr. , 17, 537-9, Dec ~ t 1946 ) 319. Essex. R. B., Radio-Craft, 17, 316, Feb. (1946) 320. Wolf, A., Inst. Radio Eng., Proc., 34, 659, Sept. (1946) 321. Stanton, L., Inst. P.adio Eng., Proc., 34, 447_56, July (1946) 322. Hastings, A. E. ~ Inst. Radio Eng. , Proc. 34, 126p_129P, Mar. ( 1946 ) _ 70 - .

323. Korrnen. N. (~946) Ins~G. Radio Eng., 324. Williams, E. M. , Inat. Radio Eng., ~ 1946 ~ 325 . Lamb, W. E . ]~0, 326. Miller, J. TIe~ 327. Glineki, G. , 328. Paine, R. C., 329 ~ Biberman, L. S 330. Mie~ke, R. C. , Proc., 34, 665P-66SP, Bent . Proc ., 34 , l8P-22P, dan. Phya. P.e~r., 70, Weston Eng. Nieces Electronic Ind. , 5, Radio 30 . me. 308_' 7 , . 1, 7-8 Sent . ~ 1946 Dee . ~ 1 946 64_5, Aug. (1946) 23-5, 36, June ~ 1946) ., Radio, 30, lid, July (~946) Waves and Electrons, I, 76W-77W, Feb. (1946) 331. Wheeler, G. J., Electronics, 19, 186, Sent. (1946) 332. Paine, R. C., Elec tronic Ind., 5 , 72-4 , 110, Now. ~ 1946 _ 71 -

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