On iterative approaches for electromagnetic rough-surface scattering problems

Iterative techniques developed for solving general systems of linear equati ons have been applied to systems resulting from electromagnetic rough-surfa ce scattering problems, Recently used iterative procedures that model the m ultiple scattering of the electromagnetic energy are shown to be mathematic ally equivalent to the application of stationary iterative procedures to th e system of equations resulting from the standard moment method. Convergenc e difficulties that are sometimes observed,vith these approaches are due to the inherent limitations of the stationary techniques. The performances of the stationary approaches are compared with that of several conjugate-dire ction-based nonstationary iterative procedures through the application to a series of scattering surfaces that yield rapidly changing conditioning of the moment-method interaction matrix. The stationary algorithms give the qu ickest convergence;,when applied to the systems with the best conditioning, but the nonstationary techniques prove much more robust in other more ill- conditioned situations.