Rough surface scattering is a current topic of interest in many diverse fields. But, despite its importance, the two most widely used solution methods, the Kirchhoff and first order perturbation methods, are valid only for a restricted range of surface types. There is a large range of surface statistics for which neither of these theories is valid. There are purely numerical solutions to the problem, i.e., the integral equation technique and FDTD method, but these methods require a prohibitively large amount of computer time and storage space for use in practical applications. A full wave method has been introduced by E. Bahar which agrees with the Kirchhoff method in its range of validity, but does not bridge the gap between the later two standard theories and does not provide understanding of the physical processes involved in rough surface scattering. Consequently, it has been a center of controversy since modifications made to improve the method seem arbitrary and are without mathematical or physical justification.

The method presented here is a new full wave method which uses equivalent currents to provide insight into the physical scattering processes. This full wave method analytically reduces to the two standard theories in their respective regions of validity and bridges the gap between the two, which was shown by comparison to the integral equation method. The results presented here are for statistically rough surfaces with Gaussian distributed heights and slopes. A Monte Carlo procedure is used to generate the radar cross section data for this new full wave method.