A Physically-Based Preconditioner for Quasi-Planar Scattering Problems

A physically-based preconditioner for iterative method of moments solutions of quasi-planar penetrable surface scattering is presented. The required preconditioner inverse operation is computed in order operations by first representing the right-hand side vector to be multiplied by the preconditioner inverse in terms of its planewave spectrum. Individual planewave amplitudes are then combined with appropriate Fresnel reflection coefficients to generate the solution for induced currents, and transformed back to the spatial domain. The proposed technique is applied in simulations of scattering from rough surfaces, and the number of iterations required to obtain a convergent solution is compared to that achieved by a banded-matrix preconditioning method. The results show that the physically-based preconditioner produces rapid convergence for surfaces with moderate heights and slopes.