Re: NEC-LIST: image modeling over lossy earth

At 03:11 PM 8/29/2007, GrantBingeman_at_cs.com wrote:
>I am looking for an article that discusses modeling a dipole over lossy
>ground in terms of Z1, Z12 and Z11, such that the image current is
>less than the
>source current above ground. In free space with no losses, two
>dipoles driven
>with equal currents allow us to find Z12 easily as Z1 - Z11. We also assume
>that Z12 = Z21.
>
>If we model a single dipole over perfect ground, we can assume that the image
>reflection is perfect, although 180 degrees out of phase with the
>above-ground source.
>
>However, if our two dipoles consist of a dipole 20 feet above 5 mS/m earth,
>and an image 20 feet below ground, does Z12 = Z21? If so, then I1
>cannot equal
>I2. NEC can tell us what Z1, I1 and Z11 are, but how do we solve for Z12 and
>I2?

Have you looked at the works of J.R. Wait? That sounds like
something he would have analyzed. I know he did loops over lossy
media, and I know he looked at wires over lossy earth (and in contact
with earth)..

James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875

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