Antenna placement for sensing buried objects by radio frequency lateral waves

Abstract

In this paper, we investigate radio wave propagation in proximity to a planar air-ground interface for the purpose of analyzing and improving the sensing of objects buried in the ground. We consider non-resonant electrically small electric dipole antennas as well as moderately directional resonant electric dipole antennas, both of which are analyzed in a variety of configurations. The ground is modeled as a uniform dielectric of finite conductivity. Our findings suggest that transmitting from beneath the ground plane can introduce significantly more complex wave propagation in contrast to transmitting from above the ground plane, by allowing the lateral and ground wave to mix. We also find that a directional sensor located just above the ground with the beam steered parallel to the ground interface is a good choice for sensing buried objects at a lateral distance due to the low loss of the lateral wave near the interface.