SPATIAL AND FREQUENCY AVERAGING TECHNIQUES FOR A POLARIMETRIC SCATTEROMETER SYSTEM

Radar scattering signals from distributed targets exhibit fading due t o interference associated with coherent scattering from individual sca tterers within the resolution volume. Uncertainty in radar measurement s which arises as a result of fading is reduced by averaging independe nt samples. Independent samples are obtained by collecting the radar r eturns from nonoverlapping footprints (spatial averaging) and/or nonov erlapping frequencies (frequency agility techniques). An improved form ulation of fading characteristics for the spatial averaging and freque ncy agility technique is derived by taking into account the rough surf ace scattering process. Kirchhoff's approximation is used to describe rough surface scattering. Expressions for fading decorrelation distanc e and decorrelation bandwidth are derived. Rough surface scattering me asurements are performed between L and X bands. Measured frequency and spatial correlation coefficients show good agreement with theoretical results.