Full wave PILE method for the electromagnetic scattering from random rough layers
Résumé
This paper presents the rigorous efficient PILE (Propagation Inside-Layer-Expansion) numerical method [1] to calculate the impulse response of the field scattered by three homogeneous media separated by two random rough surfaces. Here, the study is applied to ground penetrating radar (GPR) (nadir angle, Ricker pulse, near or/and far field) for nondestructive pavement survey by taking the roughness of the surfaces into account and by calculating the contribution of each echo coming from the multiple scattering inside the layer. The PILE method starts from the Method of Moments (MoM), and the impedance matrix is inverted by blocks from the Taylor series expansion of the inverse of the Schur complement. Its main use is that it is rigorous, with a simple formulation and has a straightforward physical interpretation. Actually, this last property relies on the fact that each block of the impedance matrix is linked to a particular and quasi-independent physical process occurring during the multiple scattering process between the two rough surfaces. Furthermore, the PILE method allows us to use any fast method developed for a single interface.