2-D EM Scattering and Inverse Scattering From Inhomogeneous Objects Straddling Multiple Subsurface Planar Layers With a Rough Surface

This letter presents the computation of electromagnetic (EM) forward scattering from and the full-wave inversion (FWI) of 2-D inhomogeneous scatterers straddling multiple subsurface planar layers covered by 1-D locally rough surface. In the forward scattering, the electric field integral equation (EFIE) is formulated and the 2-D Green’s functions are evaluated by the transmission-line analogy method and the buried object approach (BOA) to account for both the reflection and transmission in the multiple planar layer boundaries and the random scattering from the locally rough surface. The computation accuracy of the forward solver is verified by comparing the simulation results with the finite element method (FEM) outcomes. Meanwhile, the additional computational cost caused by the rough surface is investigated in numerical experiments and also explained in theory. It is shown that, for the numerical case in this letter, the forward solver needs nearly 90 times computation time and consumes nearly 30 times memory when the rough surface is present compared with those when it is absent. Meanwhile, In FWI, the variational Born iterative method (VBIM) is adopted to reconstruct multiple scatterers straddling multiple subsurface planar layers when the rough surface is present or absent. Numerical experiments show that neglecting a rough surface with the root mean square (rms) height of 0.1 m almost causes the failure of the inversion.