Electromagnetic Scattering From a Rough Layer: Propagation-Inside-Layer Expansion Method Combined to an Updated BMIA/CAG Approach

An efficient method is developed to calculate the bistatic scattering coefficient (BSC) from a stack of two one-dimensional rough interfaces separating homogeneous media. The propagation-inside-layer expansion (PILE) method recently published by Dechamps was efficient with a complexity O(N
²
) (N being the number of samples per interface). To reduce this complexity, a fast method valid for a single rough surface, the banded matrix iterative approach/canonical grid (BMIA/CAG) is combined to the PILE method. Furthermore, the calculation of the coupling interactions between both interfaces are also accelerated using a new method similar to the BMIA/CAG. The PILE method reaches then a complexity of only O(NlogN). A study of the convergence of the PILE is done and compared to another efficient method, the forward-backward.