Performance investigation of patch and bow-tie antennas for ground penetrating radar applications

Ground Penetrating Radar (GPR) uses electromagnetic waves to detect objects beneath the earth's surface. Even though signal processing plays a significant role in GPR performance, the quality of the acquired data is also dependant on the antenna and the associated electronic circuitry. Bow-tie antennas are a popular choice in GPR systems because of their lightweight design, planar structure and ultra-wideband characteristics. Recent advances in planar microstrip antenna design have thrown up lots of possibilities for this antenna type in GPR applications. In this paper, a comparative analysis of a planar microstrip antenna and a bow-tie slot antenna is presented. Both the antennas are designed for a centre frequency of 1.5 GHz, and are fabricated on Flame Retardant 4 (FR4) substrate. The planar microstrip antenna is fed by a microstrip line, whereas the co-planar waveguide feeding is used for the bow-tie antenna. The bow-tie antenna exhibits a measured bandwidth of ∼65%, with minimum return loss of -33.60 dB at 1.46 GHz. On the other hand, the microstrip antenna exhibits a return loss of -30.53 dB at its centre frequency of 1.51 GHz.