A complete electromagnetic simulation of a ground penetrating radar for mine detection: theory and experiment

Ground penetrating radar (GPR) systems are electromagnetic systems used in detecting objects buried in the Earth. The U.S. Army is investigating a particular GPR, a separated aperture sensor, as a method for detecting buried land mines. The sensor consists of transmitting and receiving dipole antennas housed in corner reflectors and separated by a metallic septum. The dipoles are tuned to the frequency 790 MHz. When this sensor is moved from a position over empty soil to a position over a target (mine) the reflection from the target causes an increase in coupling between the antennas and the resultant increase in coupling is used to detect the buried mine. In this paper, a complete three-dimensional finite-difference time-domain (FDTD) analysis of the separated aperture sensor is described. A similar FDTD analysis of a pipe detection GPR was described in Fang and Wu (1995). The geometry for the FDTD numerical model is shown. The FDTD simulation includes all details of the detector: the dipoles, the tuning stubs attached to the dipoles, the corner reflectors, and the septum. It also includes the Earth and the buried mine. The boundaries of the FDTD grid are terminated using the generalized perfectly matched layer (GPML).