Reducing the Induction Footprint of Ultra-Wideband Antennas for Ground-Penetrating Radar in Dual-Modality Detectors

Abstract

The combination of metal detection (MD) and ground-penetrating radar (GPR) has been successfully deployed to combat the threat from buried anti-personnel landmines. A number of issues arise from the close integration of these two sensing modalities. One issue is the proximity of the metallic GPR antennas to the MD coils, which affects the performance of the MD due to the eddy currents created within the GPR antenna structure. In this paper the effect of traditional solid bowtie antenna design on a MD is investigated, and avenues for the reduction of the eddy currents are explored. Three modifications to the solid bowtie design are proposed and evaluated. This paper presents measurements of the MD response to all four antenna designs using a magnetic induction spectroscopy sensor. It was found that the MD response to the bowtie antenna can be reduced by 91% to 98% across the MD operating frequency band, without significantly altering the RF performance, such as reflection and transmission coefficient and radiation pattern.

Mutual coupling effects in 2×2 antenna array for ground penetrating radar on multilayered soil

“…For example, Vivaldi antennas in GPR applications [11] [14] offer high gain and directivity; however, bandwidth is limited to the radiating frequency and depth range is small in most cases. Bigger depth ranges, up to 7 m [10], have been demonstrated by GPR systems with antennas with special geometries, like bowtie [10], [15] and low profile [13]; however, even further depth ranges are needed to meet the requirements of our field of application in Caral. Moreover, the complexity of the multi-layered soil could affect the working bandwidth of the antenna, making it more difficult to discern buried objects.…”