Wideband partially-covered bowtie antenna for ground-penetrating-radars

In this paper, wide band transmitting and receiving antennas; each composed of a bowtie partially covered by an open conducting box; are proposed for ground-penetrating-radar ( GPR) system. The inner walls of the conducting box are covered by a lossy coating which is composed of a number of layers with a conductivity profile designed to achieve better characteristics of the bowtie antenna. The Finite-Difference Time-Domain ( FDTD) method is applied to simulate the radiating and receiving antennas, the buried target and the wave propagation in the lossy ground soil over the frequency band of operation. The performance of the proposed system is examined as regards the antenna characteristics and the buried target detectability. The impedance and voltage standing wave ratio ( VSWR) of the partially covered bowtie antenna are presented over a wide frequency range. The capability of the proposed GPR system to detect targets buried in a ground soil is examined by investigating the change of the coupling between the transmitting and receiving antennas due to the presence of a buried target. The effect of the ground soil on the antenna characteristics is studied for some common types of real soils when the GPR system is placed at different heights above the ground surface.