Full-wave analysis of cavity-backed resistively loaded bow-tie antennas for GPR applications

In this paper, the design and full-wave analysis of cavity-backed circular-end bow-tie antennas for ground-penetrating radar applications are presented. A suitable resistive loading of the radiating structure is employed to achieve an ultra-wideband behaviour and, at the same time, to meet the occupation volume requirements of modern subsurface radars. The optimal loading distribution is determined by means of a locally conformal finite-difference time-domain numerical procedure, useful to accurately analyse electromagnetic structures having complex geometrical and electrical characteristics, taking into account the impact of the ground, modelled as a lossy homogeneous half space. Emphasis is placed on the investigation of the antenna near-field in order to gain useful information about potential EMC/EMI issues that could involve nearby electronic devices, as well as the impact of the resistive loading on radiation efficiency.