Ultra-wideband transmit/receive antenna pair for ground penetrating radar

Experimental results from a novel compact transmit/receive antenna pair consisting of two loss-loaded bow-tie monopole antennas are described. Instead of using a distributed resistive loading of the antenna, a broadband microwave absorber is applied as a lossy dielectric loading of the bow-tie elements. The antenna pair has a number of remarkable features. It is characterised by a high bandwidth (400-6000 MHz), a low cross-coupling, and a sharp impulse response with low reverberation. The radiation pattern maintains the same shape and orientation across the whole bandwidth, with an E-plane beamwidth ranging from 100° to 40° and a maximum antenna gain of 3.0 dBi. The input impedance is resistive, and has a value of 75 Ω over a wide frequency range. Furthermore, the input impedance is not affected by the presence of the soil when the antenna is placed on the ground surface