Modeling of EM Wave Coherent Scattering From a Rough Multilayered Medium With the Scalar Kirchhoff Approximation for GPR Applications

This article presents a new asymptotic modeling of electromagnetic (EM) wave coherent scattering from a rough multilayered medium, based on the scalar Kirchhoff-tangent plane approximation. The proposed EM model is developed to simulate a realistic ground-penetrating radar (GPR) signal that considers the interface roughness of the multilayer. It allows us to investigate the influence of the interface roughness on the amplitude of the GPR echoes coming from the multilayered medium. Sounded multilayered medium generally has a low contrast between the successive layers, so that the multiple reflections inside each layer may be neglected; this assumption will be evaluated. The very low computational burden of this EM method is an important advantage as compared with a rigorous numerical method. First, numerical results in the frequency domain are presented to validate the proposed model, by comparison with a reference method based on the Method of Moments (MoM). Then, numerical results in the time domain are presented to analyze the behavior and performance of this new method, and the impact of both the interface roughness and the medium conductivity on the results.