BACKSCATTERING ENHANCEMENT FROM SURFACES WITH RANDOM IMPEDANCE

Intensity enhancement in the retroreflection direction is studied for waves scattered by a random interface which has a bound state (surface wave). We have found that the enhanced backscattering peak appears as the result of competition of two mechanisms: multiple scattering of the surface wave along the interface, and its leakage to the upper halfspace. The last is the important difference from surface scattering, which shifts the diffuse pole and eliminates in a natural way the divergence of second moments, which is the crucial difficulty of existing theories. New results, valid when there is no real absorption in the medium, are obtained for the diffuse scattered intensity as a function of angles near the antispecular direction.