Wave scattering from lossy dielectric random rough surfaces using the physics-based two-grid method in conjunction with the multilevel fast multipolemethod

To study wave scattering from random lossy dielectric rough surfaces with l arge permittivities using the method of moments, a dense grid is needed for accurate results. A dense grid requires more CPU and memory. The physics-b ased two-grid (PBTG) method can reduce both CPU and memory requirements. In this paper, the PBTG is used in conjunction with the multilevel fast multi pole method (FMM) to solve wave scattering from one-dimensional random loss y dielectric rough surfaces. The proposed algorithm has the computational c omplexities of O(N-dg) for near-field interactions and O(N-cg) for nonnear- field interactions, where N-dg and N-cg are the number of sampling points o n the dense and coarse grids, respectively. Using the proposed algorithm, w ave scattering from Gaussian and non-Gaussian rough surfaces is investigate d and illustrated. Special emphasis is put on checking, the accuracy of the algorithm and energy conservation.