The use of dual-polarization radar data to predict attenuation from precipitation on Earth-space paths

The effect of precipitation on microwave communications between Earth stations and satellites was estimated by predicting the excess attenuation due to the precipitation, from radar data. Site diversity performance was investigated as a function of frequency (11, 14 and 20 GHz), elevation angle and site separation. The use of differential reflectivity measurements to improve attenuation predictions was tested. The dual polarization technique gives good attenuation predictions at 11 GHz. At 14 and 20 GHz, cloud attenuations are significant, but do not affect radar predictions of precipitation attenuation. Elevation dependence in the CCIR model works well for the time percentages 0.01% and 0.1%.