Backscattering enhancement in radar cross-section for concave-convex targets in random media

Abstract

Using the method that assumes a current generator together with Green's function to get the scattered waves in random media, the authors have evaluated the normalized radar cross-section (RCS) (NRCS) of complex concave-convex targets in random media to that in free space for the interval 0.1/spl les/ka/spl les/15. In this work, they assume random medium parameters: L, B/sub 0/, l so that waves around the target are incoherent and the spatial coherence length (SCL) keeps a finite value, because this assumption is needed for backscattering enhancement. They have investigated numericaily the NRCS in three regions of ka compared to SCL. For ka/spl Lt/SCL, NRCS equals two due to the double passage effect on waves in random media. This value of NRCS holds apart from incident angle and polarization. For the case of convex portion illumination and for ka/spl sime/SCL, NRCS oscillates obviously around two with some anomalous increases in the NRCS for H-wave incidence due to coupling of direct and creeping waves. While for ka>SCL, the NRCS slightly oscillates around two with increasing ka. On the other hand, for concave portion illumination, it is obvious that NRCS has a similar descending behavior with ka for E and H-wave incidences because of the effect of SCL of incident waves in both ranges of ka/spl sime/SCL and ka>SCL. Also it has found that NRCS changes clearly with complexity of target.