Three-dimensional reverse time migration of ground penetrating radar data based on electromagnetic wave attenuated compensation

The strong attenuation characteristic of high-frequency electromagnetic wave propagation in underground media with high conductivity is not considered in conventional Reverse-Time Migration (RTM) of Ground Penetrating Radar (GPR) data, resulting in low image quality in high attenuation areas. In addition, actual underground media are present in a three-dimensional (3D) space, thus the 2D RTM of GPR data is difficult to achieve the exact homing and complete convergence of diffracted waves. To solve this problem, a 3D GPR RTM algorithm based on electromagnetic wave attenuated compensation is proposed in this paper. In this approach, a 3D finite difference time domain method is used to calculate the forward and reverse time extrapolation of the electromagnetic field and compensation of attenuated electromagnetic waves is conducted by changing the sign before the attenuation term of the electromagnetic wave equation which contains conductivity. The zero-time imaging condition is employed to obtain the imaging results of underground 3D space. Then, the simulated 3D GPR data of two typical models is processed by using this program, and compared with conventional RTM results. The comparison demonstrates that the 3D GPR RTM algorithm based on attenuated electromagnetic wave compensation can effectively compensate the electromagnetic wave propagation in the underground attenuated media, and imaging accuracy and resolution of the high-conductivity area can be greatly improved and has better anti-interference ability, which is more helpful to the subsequent interpretation of GPR profiles.