A fully three-dimensional simulator for pulse borehole radar using the hybrid FDTD/PSTD

A 3-dimensional FDTD simulator is implemented for the detection of an underground tunnel by employing a cross-borehole pulse radar. The antenna and underground tunnel are modeled equivalently by employing the thin-wire model and the contour-path scheme, respectively. In various underground situations, the received radar signals are calculated numerically. But the FDTD simulator requires large computational resources because its spatial sampling grid is very fine. As a detour, a hybrid FDTD/PSTD method is suggested here. Since the spatial sampling grid of PSTD is coarser than that of FDTD, the hybrid FDTD/PSTD method may be expected more efficient than the FDTD method. The possibility of a hybrid FDTD/PSTD simulator is verified in a simple 1-dimensional case.