Degree of polarization of radar backscatters from a mixed target

When an extended radar target is a mixture of two kinds of random media, the degree of polarization of a backscattered wave from the target changes with the mixing ratio of two random media. Using measured modified Mueller matrices of (a) four dielectric surfaces with different roughness, and (b) a tree (Japanese pine), dependencies of the degree of polarization on the mixing ratio are discussed. A unified relation between the mixing ratio and the degree of polarization that does not depend on the difference of the four surfaces is derived. The approach discussed in this paper will provide a potential tool for analyzing mixed-target areas in polarimetric SAR images.