Analysis of empirical rain attenuation models for satellite communications at Q to W band frequencies

This paper examined the use of existing empirical rain attenuation models for earth-space paths links for frequencies at Q band and greater. Extrapolation of these models that are based on low frequency (<; 20 GHz) data results in significant spread in attenuation predictions at 50 GHz and higher. Extrapolation of models based on the p = 0.01% rainfall rate to higher frequencies is limited due to the power law dependence of rain attenuation. Models that use the full rainfall rate to map attenuation to the corresponding rainfall rate distribution are subject to inaccuracies due to the artificial mapping of all sources of attenuation to a single rainfall rate. Comparison of the ITU-R P.618 attenuation model to available Q/V band data suggests limitations on the useful frequency range and highlights the importance of attenuation combining methodology.