Method for Retrieving the True Backscattering Coefficient from Measurements with a Real Antenna

Measurements made of the power backscattered by a surface at angles near nornal incidence include contributions due to both coherent and incoherent scattering. Additionally, these contributions are weighted by the antenna pattern. Using a theoretical model to describe the backscattering from a rough soil surface, a procedure is developed for retrieving the true angular pattern of the backscattering coefficient σ0 from measured estimates of a σ0 , where the measured estimate is based on the usual assumption that σ0 is approximately constant over the angular extent of the antenna beam for narrowbeam systems. The retrieved patterns of σ0 were then used to evaluate the dependence of σ0 on soil surface roughness at 1.5, 4.25, and 7.25 GHz.