SPECTRAL ITERATIVE ALGORITHM FOR RCS COMPUTATION IN ELECTRICALLY LARGE OR INTERMEDIATE PERFECTLY CONDUCTING CAVITIES

A novel algorithm designed to compute efficiently and accurately the h igh-frequency electromagnetic scattering from open-ended waveguide cav ities is presented. The cavity is converted into a stepped-waveguide m odel so that the field spectra are propagated, forward and backward, a long each waveguide section. As boundary conditions for perfect electr ic conductors are applied via image theory, they are of local nature a nd take into account only the first-order interactions between each pa ir of waveguide sections. Accordingly, additional forward-backward ite rations must be performed if multiple interactions are to be taken int o account. Finally, the radar cross section due to the interior irradi ation is calculated by a Kirchhoff-based aperture integral. Good agree ment with Method of Moments and Hybrid Modal solutions is found, as we ll as with experimental data, for two-dimensional and three-dimensiona l cavities with rectangular cross section.