A Bi-Iteration Model for Electromagnetic Scattering from a 3D Object above a 2D Rough Surface

Aiming to accurately solve the extra-large-scale electric and composite electromagnetic scattering from an object above a randomly rough surface, a bi-iteration model is proposed in this article that includes outer iteration and inner iteration. The outer iteration, based on the analytical/numerical methods, is used to calculate the electromagnetic scattering from the rough surface and the object due to their respective computational costs and accuracy. The inner iteration is applied to solve the scattering simulation of a complicated rough surface and to improve its computational precision by using the iterative physical optics. Meanwhile, to accelerate the convergence of the iterative physical optics, the forward-backward methodology and its modification with an under-relaxation iteration method are applied to solve the scattering of the complicated rough surface states. The efficiency and accuracy are demonstrated by some experiments. Therefore, compared with the common methods, the proposed model can effectively solve the more complicated scattering problem from a 3D object above a 2D rough surface.