Development of Ray-Optical Methods for Studying the RCS of 2D Targets on a Rough Sea Surface

摘要

The radar scattering from ship-like targets on a rough, time-varying sea surface is investigated using computational techniques developed specifically for this problem. A spectrally accelerated generalized forward- backward method is used to study the time-varying RCS, and to generate reference solutions for more approximate ray-optical techniques. The ray techniques decouple the target from the sea surface via a plane wave expansion for the sea scattered field in the vicinity of the target. Much larger targets may be analyzed using ray methods, but the accuracy is limited. It is found that the time-varying RCS of a target on a moving sea surface can peak higher than the RCS of the same target on a smooth surface. It is also found that the variation (maximum deviation) of the RCS with time increases with a decreasing coherent (time independent) component of the sea scattered field which illuminates the target. The magnitude of the coherent component is a function of frequency and elevation angle as well as the surface roughness. The roll angle of the target on the sea surface also strongly affects the RCS level, and is another useful indicator of the RCS variation.