Calibration techniques for Olympus 20 GHz switched polarization satellite beacon measurements

A measurement of the complete transmission matrix of a slant path using a switched polarization satellite beacon needs to be properly calibrated in both amplitude and phase to yield the best characterization of the hydrometeors which affect propagation. For accuracy, error contributions from the satellite and earth station should be separated and corrected individually. It is shown how this can be achieved by indirect methods which rely on minimal theoretical expectations of the form of the transmission matrix. Methods to calibrate the amplitude and phase offsets of the satellite and receiver, and to assess the satellite polarization purity, are demonstrated using the Olympus satellite at 20 GHz. Small amplitude imbalances in the beacon are found and corrected, but a large correction for an unexpected phase offset is required. Good polarization purity of the beacon is inferred.