Use of the Glistening Surface Concept in Rough Surface Scattering

摘要

Calculations of diffuse power scattered from a rough surface have typically used the concept of a glistening surface over which a centerline-varying surface cross section is integrated. The usual form of that surface is derived for relatively smooth surfaces and contains several other constraints that are not always evident. In this report, we will address the limitations on this definition and several alternative forms that are less restrictive. We will compare them with a more realistic solution in which the azimuthal variation in the surface cross section is taken into account and the integration is across the entire signal footprint on the surface. The standard scattering surface dimensions are determined under constraints on both the antenna heights and the surface width. In the report, we analyze the effect of removing those constraints. In addition, we consider a second formulation in which one of the antenna terminals of the bistatic system is considered to be sufficiently distant so that it is treated as being at infinity. We examine the different boundary values for the glistening surface based on these different assumptions and compare the resultant scattered power levels with the azimuthally varying cross section results. One of the most important conclusions is that the use of the centerline normalized cross section models can lead to calculated diffuse power levels that are in disagreement with the results for the more exact solution in which both the azimuthal variation in sigma deg. is accounted for and the integration is always across the entire radar footprint rather than a calculated glistening surface width.