Perfectly matched layer and piecewise-linear recursive convolution for the FDTD solution of the 3D dispersive half-space problem

A 3D finite-difference time-domain simulation of a dispersive, inhomogeneous half-space problem is described. The formulation uses the perfectly matched layer (PML) absorbing boundary condition (ABC) extended to dispersive media. The dispersion is characterized by a two-species Debye model with parameters taken from reported experimental data of soils with different moisture contents. The time-stepping scheme for the electric field uses the piecewise-linear recursive convolution (PLRC) method. For homogeneous half-space problems, the simulation results are compared against results from numerical integration of Sommerfeld-type integrals. To illustrate its applications, the inhomogeneous half-space simulations include results from the ground penetrating radar simulated response of buried objects in realistic soils.