Properties of attenuating and depolarizing atmospheric hydrometeors measured on a 19-GHz earth-space radio path

One year of propagation data were obtained for a 19-GHz earth-satellite path terminating at Crawford Hill, New Jersey. These data were analyzed to determine the depolarizing and attenuating properties of liquid (rain) and solid (ice) hydrometeors along the path. The observed projections of the symmetry axes of ice and rain hydrometeors were found, generally, to lie near the horizontal and vertical planes. Ice deviates from this orientation more than rain; ice occasionally is found at any possible orientation. The observed differential attenuation and differential phase for a given copolarized signal attenuation were lower than those seen on terrestrial paths. Present terrestrial rain models do not adequately describe these results. Maximum depolarization was observed to occur for linear incident polarizations near 45°. This maximum depolarization is sufficient to significantly affect the performance of dual-polarization satellite communications systems. Depolarization close to the minimum attainable for instantaneously optimized linear incident polarizations was observed most of the time for fixed vertical and horizontal polarizations. These minimum depolarization levels were low enough to have little effect on most dual-polarization systems.