A Compact TEM Horn Antenna for Ground Penetrating Radar

A small TEM horn antenna for ground penetrating radar (GPR) applications is proposed in this paper. TEM horn antennas are appropriate for GPR applications due to their wide bandwidth, high gain, and good efficiency. The operative band of a GPR antenna is a trade-off between the penetration depth and desirable resolution. At low frequency, radar has more penetration depth but the possible problem is the big size of antenna. So the aim of this study is to design a small size horn antenna with low cut-off frequency. The band is extended to the lower frequency with three major changes with respect to a standard horn: 1) using the TEM double-ridged waveguide with a cylindrically shaped cavity as transition section; 2) putting absorbing material in the back plate of the antenna; 3) using a semi-circle of radius 5 mm set on the top of the flare end section. The proposed antenna has a small size of (311 mm × 265 mm × 385 mm) and the simulated results demonstrated good impedance matching from 100 MHz to 2.5 GHz under a return lass (S11 ≤ -10 dB), and good radiation pattern. The designed TEM horn antenna is modeled in free space and in contact with the ground. The capability of the antenna for detecting buried objects is confirmed with simulation.