Comparison among three bowtie antennas for subsurface imaging using ground penetrating radar

Antenna is a key part of a ground penetrating radar(GPR) system for subsurface imaging. To provide a high resolution, a GPR antenna has to work over an ultra-wideband and a relative constant phase center, which means it has to radiate and receive a short pulse with a small time sidelobe (ringing). Bowtie antenna is widely used in the mature commercial GPR systems. In this paper, we simulate three types of bowtie antenna and analyze the result. The main difference among the antennas is the structure of the arms, two of which are from GSSI and MALA. The third one is designed by us. As we all know, the shielding cavities and the absorbing materials have a large influence on the performance of the GPR system. Thus, we construct the antennas containing the shielding cavities and the absorbing materials. Considering the application of GPR in the civil engineering, we have built up the model surrounded by the concretes, which approximates the real working circumstance. The thickness of the concretes is 0.5 m. The transmitting antennas and the receiving antennas locate on either side. Fig. 1 shows the gain of the antenna, and Fig. 2 shows the receiving pulse. From the two figures, we can conclude that the type3 has a better performance including the widest band and the lowest sidelobe.