Strong backscattering enhancement for partially convex targets in random media

Abstract

Earlier work pointed out that the radar cross section (RCS), owing to the double-passage effect on waves propagating through random media, is enhanced by a factor ranging from one up to three. However, our study has manifested numerically a strong enhancement in RCS of targets with concave-convex surfaces in continuous random media, by taking account of boundary conditions of waves on targets. We have found that when a plane wave illuminates a convex portion of the concave–convex conducting target in a random medium, the factor of enhancement oscillates about two with target size. Moreover, this enhancement becomes quite large at certain target shapes and also under a specific condition of target size and spatial coherence length of the incident H-wave. The large enhancement is considered as an anomalous feature in the behaviour of backscattered waves in random media. By analysing the scattering problem for beam-wave incidence on the same target in free space, we manifest the mechanism of such anomalous enhancement.