Digest on Literature on Dielectrics Volume X (1947) / Chapter Skim
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Electrical Properties of Matter
Electrical Properties of Matter
Pages 1-71
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From page 1... ...
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 dielectrice 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.
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From page 2... ...
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 Temperature; 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 Determining 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
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From page 3... ...
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 calculated from.
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From page 4... ...
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?
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From page 5... ...
In a second paner, Ogg) 3 outlines briefly the theoretical considerations which preceded the e~erimental discoveries relating to the properties of metal ammonia solutions.
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From page 6... ...
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.
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From page 7... ...
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.
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From page 8... ...
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.
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From page 9... ...
The variation of the dielectric constant of the nl-ohase of p 9 ~'~azoxyaniso] by magnetic fields has been investigated by Maier32.
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is ex_ claimed from the fact that these solids either have a high dielectric 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.
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Data are given for the dielectric constant of this material at lol2 mcO an]
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From page 12... ...
The dielectric 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.
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From page 13... ...
01' 6 ', TOW 1088 9 and a positive temnere~re coefficient of dielectric 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 hexagone~ structure of predominantly ionic bond character.
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From page 14... ...
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, ~ .
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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.
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From page 16... ...
Lithium alkyl s may thus be reg~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 constants at 20oC.
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From page 17... ...
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]
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From page 18... ...
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-.
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From page 19... ...
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.
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From page 20... ...
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]
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From page 21... ...
es measured are like~r.'ise different. At loser frequencies, currents, rouge, inductance, ca~aci~Gance, resistance and frequency measurements are of prime importance; in micro~.ra~re measure_ Detente, Moorer attenuation, wavelength, standing wave ratio and position are the Quantities ~ought.
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From page 22... ...
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.
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From page 23... ...
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 Joining To uniform transmission lines.
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From page 24... ...
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.
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From page 25... ...
Eem439elucidates the nuzzling phenomenon of decreasing attenuation with increasing frequency which occurs in a few isolated instances, by treating the guides concerned as limiting cases of a "aide of snore general share in the interior of Rich the waves display the normal properties characteristic of ret in guides generality. The equations of the elect~c>_magnetic field, cut-off frequencies ~d attentuation descr'bing the isolated cases are then, in like manner, deduced as limiting caSes from Choose appropriate to a guide of General shape.
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From page 26... ...
The tonics; included in Hill' ~ O paper are: the stability of magnetrons, 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.
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From page 27... ...
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.
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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.
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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.
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From page 30... ...
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 detectors 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.
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From page 31... ...
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.
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From page 32... ...
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.
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From page 33... ...
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.
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From page 34... ...
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.
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From page 35... ...
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 phenomena 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.
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From page 36... ...
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.
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From page 37... ...
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.
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From page 38... ...
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 undergo a transition in a steady homogeneous electric field by an oscillating electric field at right angles to the deco component.
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From page 39... ...
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.
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From page 40... ...
material handling, temperature control , maintenance of equipment, ant testing instruments required.
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From page 41... ...
. Coaxial ~ abl es and transmission lines are an important component of high-frequency and micro are equipment.
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From page 42... ...
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.
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From page 43... ...
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.
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From page 44... ...
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
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From page 45... ...
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.
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From page 46... ...
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 dielectric constant and cooker factor measurements on solid d1electric materials at wa.ve-lengths below 50 cm.
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From page 47... ...
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.
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From page 48... ...
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 Modificetion of the Resonent Cavity Method for Dielectric Measurements at ~ Fixed Frequency ty Beker5 end a.
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From page 49... ...
. Sprouts and Linder281 are concerned with resonant cavity measurements, using a cathode-ray oscilic~scope as indicator.
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From page 50... ...
Using Llghthouse Tubes axld Cavity Resonators in the U.H.F. Region - Rand309.
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From page 51... ...
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~.
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From page 52... ...
Packard, L.E. ~ Electronic Inds., 5, 42-5, Dec.
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From page 53... ...
Electronic Inde., 5, 6S, Mar.
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From page 54... ...
; Electronic Inde ., 5, ll2, ] ~n~ ~946~ Thermocour'1e Ammeters for Very High Frequency.
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From page 55... ...
Lynn Engineering Co.; Electronic Ind., 5, ll2, Mar.
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From page 56... ...
BIBLIOGRAPHY Matllre , 158s , 121_4, July ~ 1946 )
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23. Field, R
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From page 58... ...
44~ Wllig B M~ ~ t`~ature$ 1573 808, Jlme (1946)
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From page 59... ...
63. Rogers, M
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From page 61... ...
) Radio News, Radio~Electr onic De~t e )
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From page 62... ...
J., Electronic Ind., 5, 80_2, 120_2, Mar.
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From page 63... ...
152. Crosby, D
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From page 64... ...
Rershterger, W Do and others, B.C.A.
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From page 65... ...
C., Electronic Ind., 5, 78-9, June tl946)
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From page 66... ...
'1946) Electronic Ind., 5, 62~3, Non.
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From page 67... ...
E., Electronic Ind., 5, 94.6, Air.
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From page 69... ...
287. Electronic Ind., 5, 75_7, 96, July (1946)
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From page 70... ...
312. Muller,, W., Electronic Ind., 5$ 7~3, ITS, 120, 122, May ( 1946 )
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From page 71... ...
Nieces Electronic Ind. , 5, Radio 30 .
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