Quadpolarization SAR Calibration Using Target Reciprocity

In this paper we present a novel algorithm for radiometric and polarimetric calibration of complex quadpolarization SAR data. It is based partially upon known targets in the image and partially upon the assumption of reciprocity of all other scatterers; no other assumptions about background scatterer statistics are required. The only manmade targets required by the basic algorithm are a trihedral-dihedral corner reflector pair for calibration at each range (a more general technique which requires two arbitrary passive targets is outlined as well). The algorithm presented here is an improvement over previous ones in that it does not require three known targets or azimuthal symmetry of the background to solve the polarimetric calibration problem. Results are presented using airborne SAR data.