An Evaluation of the U.S. Navy's Extremely Low Frequency Submarine Communications Ecological Monitoring Program (1997) / Chapter Skim
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Appendix B
Appendix B
Pages 157-162
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From page 157... ...
The wavelength at 76 Hz is very large, compared with the longest dimension of the body, so the quasistatic field theory can be appropriately applied to calculate the induced electric field in the body (Michaelson and Lin 1987~. For uniform external electric and magnetic fields, the magnitude of the induced electric field inside a homogeneous dielectric tissue sphere resulting from the applied electric field is Ee = 3/cEo (Bar)
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From page 158... ...
However, they are dependent on the orientation of the applied electric and magnetic fields with respect to the major axis of the body. in particular, because a > b, the higher induced field is associated with an applied magnetic field oriented along the minor axis of the body.
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From page 159... ...
The exposure parameters considered are applied electric fields of 10-5,000 mV/m and applied magnetic fields of 1.0-50 mG. Results are shown in Figures B-!
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From page 160... ...
As shown in Figure B-l, the magnetically induced electric field varies with both body size and magnetic field. For a lOO-mg insect, the maximal induced electric field can vary from 6.9 x lo-s mV/m at 1.0 mG to 3.4 x i0~3 mV/m at 50 mG.
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From page 161... ...
The results of a vertically oriented magnetic field are shown in Figure B2. Induced electric fields depend both on the width of the tree stand and on the magnitude of the applied magnetic field.
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From page 162... ...
Calculations based on these simple models suggest that the electric field induced in a 25-m tree by a vertically oriented electric field could be as high as 5,000 mV/m and that induced by a horizontally oriented magnetic field could be as high as 29.S mV/m. It is emphasized that because of shielding and other phenomena, the applied or impinging electric field would decrease in strength with distance from the antenna wire and as a function of the landscape.
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