MILLIMETER-WAVE BACKSCATTER FROM DESERT TERRAIN

The association of millimetric radar clutter and terrain characteristics measured on a variety of desert surfaces is reported. Close-up photogrammetric analysis provided digitised profile data from which measures of surface roughness have been obtained, and the dielectric properties of surface materials and vegetation are estimated empirically with data obtained from field samples. The data are used to obtain empirical multiple regression models, which suggest that for 94 GHz backscatter from desert terrain copolar backscatter is dominated by surface scattering, apparently so much so that it is reduced by the presence of vegetation (which is volume-scattering), the latter contrary to what has been found at lower microwave frequencies. The methods also suggest that crosspolar backscatter is dominated by volume scattering and appears to be unaffected by sparse vegetation.