FDTD Simulation of GPR Electromagnetic Wave

The Ground Penetrating Radar (GPR), which is an effective, speedy, continuous and non-destructive testing equipment, its application in pavement has been the international hot subject since 1980s. This paper introduces the basic theory of Finite Difference Time Domain (FDTD) by analyzing the characteristics of electromagnetic wave propagation in pavement, especially from 1-dimension FDTD equation, soft source, effective parameter of layered boundary and Absorbing Boundary Condition (ABC), which have the greatest significance in FDTD simulation of GPR. Then a forward air coupling GPR propagating in layered medium model is established. Moreover, the validity of this forward model is examined through several simulated and actual cases with the maximum error one of 2%. This model develops a new concept for practical and accurate interpretation of GPR reflection data, which can develop a new algorithm to calculate the thickness of pavement's layer, and even develop a new way to measure the moisture and density of pavement's layer in non-destructive testing.