Gain And Front To Back Ratio Improvement Of UWB Bowtie Antenna Using Reflectors For Ground Penetrating Radar Applications

Abstract

The gain and front to back ratio of UWB bowtie antenna is improved in this paper to meet the requirements of Ground Penetrating Radar (GPR) applications. GPR antennas must have good gain toward the ground to achieve more ability of penetration, and high front to back (F/B) ratio to save the power and reduce external electromagnetic interferences. This is done by adding planar and parabolic reflectors to the proposed antenna, which has fractional bandwidth (FBW) of 138% within (1-5.45) GHz. The simulation has been carried out using CST Microwave Studio to study the effect of each reflector on the gain and F/B ratio. Toward the ground, planar reflector achieves maximum gain improvement of 4.75 dB, and maximum F/B ratio of 14 dB with bandwidth (1-2) GHz only. So, it cannot change the general behavior of main antenna gain. While parabolic reflector achieves maximum gain improvement of 35.35 dB, maximum F/B ratio of 33.79 dB over the whole bandwidth, and FBW of 156% within bandwidth (0.92-7.44) GHz. According to these results antenna with parabolic reflector is fabricated, and the gain and return loss is measured. The measurements show a good agreement with the simulation results.