Simulation of GPR in anisotropic medium by finite element time domain method

Abstract

A two-dimensional finite element time domain (FETD) algorithm for simulation of ground penetrating radar (GPR) on an anisotropic medium with conductive loss is described. In this algorithm, the finite element method is used to discretize computational area by using the unstructured Delaunay mesh and Newmark difference method for time discretization. The anisotropy of the medium is modeled be orthorhombic symmetry and expressed as the permittivity and conductivity tensors of different propagation directions. The convergence property of our algorithm is verified by comparing it with the analytical solutions of homogenous isotropic and anisotropic media. The influence of material anisotropy to phase velocity and attenuation coefficient of electromagnetic waves are analyzed by comparison with snapshots of homogeneous isotropic and anisotropic media. A model consisting of a cylinder target embedded in an anisotropic medium is further tested to understand the propagation characteristics of the reflected wave. The results demonstrate that material anisotropy can cause significant amplitude and phase velocity distortions. The proposed FETD algorithm for anisotropic medium can be applied to calculate anisotropic GPR problems with high accuracy.