Improving the GPR Detectability Using a Novel Loop Bowtie Antenna

Abstract

The Ground Penetrating Radar (GPR) technique finds immense applications in civil engineering today, as the most suitable approach for non-destructive testing of pavements, highways, concrete structures, and more. The major challenge in carrying out a GPR evaluation is that the properties of the probed medium are usually unknown. The permittivity and conductivity of the medium may vary from those of air to water. The electromagnetic waves also have a frequency dependent attenuation. The ability of GPR to detect signals reflected and scattered by the targets largely depends upon the antenna performance. This paper studies a novel 11:1 wideband loop bowtie antenna with very good radiation properties in the entire operating bandwidth. Synthetic and experimental results are presented for the return loss and gain of the antenna. Furthermore, experimental results are presented for the radiation patterns in the E- and H-plane. We also used the antenna to measure B-scans over two different pipes, a bamboo, and a reinforced concrete structure. All results obtained with the proposed antenna have been compared with results obtained by using a RC loaded antenna. It has been found that the loop bowtie antenna has excellent detection capability and produces less clutter. The loop loading technique can be applied to existing antennas for improved GPR imaging. This will improve the detectability of GPR by improving the target return signal.