CALIBRATION AND APPLICATIONS OF POLARIZATION-CORRELATING RADIOMETERS

Hardware and associated software for non-mechanical rotation of the po larization basis of a dual linearly-polarized cross-correlating radiom eter are demonstrated. The technique requires precise measurement of t wo orthogonal-mode antenna temperatures along with cross-correlation o f the two orthogonal-mode field amplitudes. Collectively, these are th e first three Stokes parameters. A polarized blackbody load was develo ped for accurate calibration of the orthogonal-mode and cross-correlat ing channels. Using the hardware, rotation of the radiometer antenna's - polarization basis by a matrix transformation was demonstrated by 91 .65-GHz near-Brewster angle scans of a polarizing water surface. The e xperimental results demonstrate the viability of the rotation techniqu e and suggest practical calibration schemes for airborne and spaceborn e polarimetric radiometers. Application of the rotation technique in m echanically-scanned polarization-sensitive imaging radiometers will el iminate polarization coupling inherent in conventional fixed-feed dual -polarization scanner designs.