Implementation of a dispersive matched layer RBC within an FDTD framework, and its application to impulse GPR studies

The problem of excessive computational resource requirements for modelling of dispersive and lossy materials is addressed with the development of high performance boundary conditions that can operate in such media. The work reports two innovations, firstly the investigation of conductivity profiles using genetic algorithm optimisation methods, and secondly the use of variable permittivity and permeability within the PML layer for effective absorption of evanescent waves. It is demonstrated that such methods can provide order of magnitude improvements in reflection coefficients over analytically derived profiles in both lossless and lossy dispersive materials. The effectiveness of the RBC is illustrated in the application of transient ground penetrating radar in soils with conductive loss using a full 3D model of an impulse GPR system, including antennas and feeds. Results are compared to published measurements