3-D EM Scattering and Inverse Scattering by Anisotropic Objects Straddling Multiple Planar Uniaxial Layers With a 2-D Locally Rough Surface

In this article, both the electromagnetic (EM) forward and inverse scattering by 3-D arbitrary anisotropic scatterers straddling multiple planar uniaxial layers covered by a 2-D locally rough surface are discussed. In the forward scattering, the 3-D electric field integral equation (EFIE) is formulated and the dyadic Green’s functions (DGFs) are evaluated based on the transmission-line analogy method and the buried object approach (BOA) to account for the EM wave reflection in multiple planar layer boundaries and its scattering from the rough surface. The additional computational cost caused by the rough surface is theoretically analyzed. In the full-wave inversion (FWI), the discretized data equation which is assembled from the total fields solved from the forward EFIE and the DGFs including the rough surface influence is solved by the variational Born iterative method (VBIM). Several numerical examples are presented to verify the computation accuracy and the additional time and memory cost caused by the rough surface in the forward scattering and to testify to the necessity to include the rough surface in inverse scattering.