FDTD simulations for ground penetrating radar in urban applications

Ground penetrating radar (GPR) is a very important tool for urban investigations. We introduce a finite difference time domain (FDTD) method to solve Maxwell's equations when the dispersive earth medium can be simulated. We give an iterative method for electrical displacement and magnetic field in a Debye medium, and a method to compute electric field from electrical displacement. The physical parameters are used only in calculating the electric field. The examples demonstrate that the electromagnetic wave in the dispersive medium attenuates very fast and the measured signals are very weak. The cavity detection and the tunnel wall inspection are numerically proven to be possible and effective.