Analytical and experimental studies of coupling between antennas over a two-dimensional ground surface of known contour

A numerical procedure is presented for computing the transfer impedance between two antennas located above a two-dimensional ground surface of known contour. The antennas are either both horizontally or both vertically polarized, and may have arbitrary radiation patterns in the vertical plane. The antennas are assumed to be high enough above the ground so that surface wave coupling is negligible but close enough so that a significant portion of the received power arrives via ground scattering. For purposes of computation, the ground is divided into a series of connected (infinite) planar strips of identical projected width. The net scattered field is computed using Green's theorem applied to each strip individually but neglecting edge effects and multiple scattering. The practical utility of this technique has been tested in a limited way by measuring the variation in coupling between two identical horizontally polarized horn-aperture antennas over a single ground contour. Provided the baseline profile is surveyed carefully at the time the coupling measurements are made, the numerical predictions are seen to be in reasonable agreement with the test data.