Dependence of Depolarization on Incident Polarization for 19-GHz Satellite Signals

Dependence of Depolarization on Incident Polarization for 19-GHz Satellite Signals BY H. W. ARNOLD and D. C. COX (Manuscript received July 20, 1978) Rain and ice crystals depolarize radio waves along earth-satellite propagation paths. The magnitude of this depolarization is a function of incident polarization angle and is minimized when polarization and depolarizer symmetry axes coincide. A technique is presented for a direct determination of the medium's attenuation and depolarization for any incident polarization, based on measurements taken at two orthogonal polarizations. Some sample results from this technique are presented, using data collected at Crawford Hill, New Jersey using the 19-GHz COMSTAR satellite beacon. I. INTRODUCTION Depolarization caused by rain and ice crystals is an important factor in the design of future satellite communication systems operating at frequencies above 10 GHz.1-2 These systems will likely use dual, orthogonal polarizations to increase transmission capacity. Quantitative knowledge of depolarization is necessary for determining the pair of polarizations that experience the least depolarization, for determining whether the isolation between any two polarizations is adequate during rain and ice depolarizing conditions, or for guiding the design of circuits for canceling crosstalk resulting from depolarization if the isolation is not adequate. Only a few measurements have been made of depolarization along earth-space propagation paths. 3 - 5 These measurements were not necessarily made at incident polarizations that produce minimum depolarization.