Full Wave Theory for Rough Surface Scattering Using the Kirchhoff Solution forPrimary Field

摘要

This final report summarizes work done under Grant DAAHO4-94- g-0035. Theobjective of the investigation was to develop a more rigorous full wave approach to rough surface scattering than that used by Bahar in his full wave method. Instead of relying on the use of telegraphists equations a local spectral expansion method was found that is applicable to general rough surface scattering, not just surfaces with roughness in one dimension only. The local spectral expansion method can be formulated so as to involve the tangential fields at the surface as the only unknowns. This is in contrast with Bahar's full wave method which involves coupling integrals between the modes used in expanding the field and is more difficult to use in an iterative procedure. The new method turns out, in the lowest approximation involving the Kirchhoff approximation for the surface tangential fields, to yield significantly more accurate results for most scattering angles. The new approach also covers a wider range of surface parameters that extend from the small perturbation regime to the standard Kirchhoff regime.