An Examination of the 'Full-Wave' Method for Rough Surface Scattering
Final rept. 1 Apr 1988-30 Sep 1989
WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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The goal of this project was to complete a study of Bahars full-wave approach to rough surface scattering that was begun under ONR support. The two proposed items of technical work have been fully completed. In the ONR-supported work, a study was begun for a simplified scattering problem Scattering from a one-dimensional 1-D surface with the Dirichlet zero field boundary condition using a Gaussian roughness spectrum. The full-wave method was implemented numerically and used in Monte Carlo calculations of the scattering cross section. Comparisons were then made with exact integral equation results, and with the Kirchholl and perturbation approximations. It was found that the full- wave prediction did not reduce to the lowest order perturbation prediction when the perturbation result was known to be accurate, as shown by exact calculations. This is contrary to conclusions reached by Bahar and is an important finding, showing that the full-wave approach is not as general as previously thought. The full-wave prediction did reduce to the Kirchhoff prediction when the Kirchhoff approximation is known to be accurate, as shown by exact calculations. In fact, the full-wave result was found to agree closely with the Kirchhoff result for all cases studied, whether or not the Kirchhoff result was accurate.
- Radiofrequency Wave Propagation