Analysis of azimuthal variation of rain attenuation

The attenuation due to rain is the main source of impairments in satellite links operating above 10 GHz. In the design of systems based on Low Earth Orbit (LEO) satellites, the analysis of the rain attenuation must take into account both azimuth and elevation variations. It requires a deep knowledge on the nature of this dependence. As measurements at several elevation and azimuth angles are not available, it is necessary to use prediction models that aim at reproducing the rain profiles of each link. This paper presents an analysis of the azimuth dependence of rain attenuation according to the size of the azimuthal window where this attenuation occurs. It is shown that the azimuthal rain attenuation windows smaller than 180° are few at higher elevation but their probability increases exponentially with the decreasing of the elevation.