Frequency Domain Reverse Time Migration of GPR with Attenenuation Compensation

High computational cost is always a critical concern for reverse-time migration (RTM), and prevents its applications to ground penetrating radar (GPR). To address this challenge, a frequency domain RTM algorithm based on the layered medium dyadic Green's function (DGF) is proposed for high-resolution and efficient subsurface imaging using GPR. To mitigate the amplitude distortion in lossy media, the attenuation compensation in the backward wavefield extrapolation is performed by modifying the computation of DGFs in layered media. The final image is reconstructed by the direct summation of all the wavefields for all the sampling frequencies in the frequency domain, instead of transforming them back to the time domain and processing them. Both numerical and laboratory experiments are conducted to verify the performance of the proposed algorithm, and the results show that our algorithm can yield almost the same subsurface image with the conventional time domain RTM algorithm, but requires less than two orders of magnitude in computational costs. The results also show that the quality of the RTM image in the conductive background medium can be significantly enhanced by compensating the wave attenuation.