Application of the spectral acceleration forward-backward method to coverage analysis over terrain profiles

The Forward-Backward (FB) method and its accelerated version (SA-FB, Spectr al Accelerated Forward-Backward) were developed to compute the electromagne tic scattering from ocean-like rough surfaces. The FB algorithm provides ve ry accurate scattering results and a very fast convergence, but its computa tional cost is still O(N-2) per iteration, being N the number of unknowns u sed to discretize the surface. The Spectral Acceleration Algorithm proposed later reduces this cost to O(N). Nevertheless, the SA-FB can only be appli ed to quasi-planar structures or slightly rough surfaces (such as the sea s urface), but it cannot be used to solve problems involving very undulating surfaces such as terrain profiles. In this paper the SA-FB method is modifi ed to enhance its scope of application to considerable undulating surfaces. It will be seen that significant changes with respect to the original form ulation as well as modifications of the integration path are necessary to g et accurate results when dealing with terrain profiles. The proposed method is presented for vertical and horizontal polarizations and for PEC and non -PEC surfaces.