A progression of high-frequency RCS prediction techniques

Attention is given to the unique features and advantages of the various methods that have been devised over the years to predict the radar cross section (RCS) of large, complex detection targets. The method of moments is unsuitable for routine large body computations, and geometric optics yields erroneous results for flat and singly curved surfaces. The theories of Keller (1957) and Ufimtsev (1957) have poor diffraction coefficients in the transition regions of shadow and reflection boundaries. In the Kouyomjian and Pathak (1974) theory, the scattering direction is constrained to lie on the Keller cone, while a method of equivalent currents, although permitting the scattering direction to be arbitrary, yields nonphysical equivalent currents. It is noted that the methods discussed do not address the problem posed by the surface traveling wave of long, smooth bodies.