| Bistatic scattering of electromagnetic waves by a rough surface consists of two components, a coherent component along the specular direction, and an incoherent component characterized by a scattering pattern over all directions. Several theoretical models have been developed to characterize bistatic scattering by random rough surfaces, for both perfect conducting and dielectric cases. To date, however, the accuracies and regions of validity of these models have been examined for only the backscattering condition, simply because almost all radar systems operate exclusively in the backscatter mode. As a result, these theoretical developments remained largely untested for bistatic scattering. This thesis investigates, theoretically and experimentally, the nature of bistatic scattering of 10 GHz microwaves from randomly rough dielectric surfaces.;The traditional Physical Optics solution is shown to not include all the lowest order dependence of the incoherent surface scattering on the surface parameters. An algorithm is presented for evaluating the Physical Optics problem for arbitrary orders of slopes. Based on this algorithm, the modified Physical Optics model incorporates all the lowest order dependence of the scattering coefficient on the surface parameters. This algorithm is also used to calculate a rough surface reflection coefficient. The resulting modified Physical Optics expressions are simple algebraic extensions to the corresponding Physical Optics expressions.;For the experimental study of bistatic scattering, a Bistatic Measurement Facility was constructed. A number of measurements of both coherent and incoherent scattering from rough surfaces with a dielectric constant of ;As an application of bistatic rough surface scattering, the Michigan Microwave Canopy Scattering model (MIMICS), a successful model for describing overall microwave back-scattering from crops and forests, is presented with additional terms describing the double bounce mechanism between a rough ground and tree trunks. |
