PREDICTION OF ATTENUATION ON SATELLITE EARTH LINKS FOR SYSTEMS OPERATING WITH LOW FADE MARGINS

A new method for prediction of attenuation on satellite-earth links is presented for systems operating with low fade margins. The method is based on modelling the physical structure of rainfall and includes, in order of importance: (1) an improved approach to combining components of fading; (ii) a non-uniform vertical on-average profile of rain spe cific-attenuation; (iii) the differing frequency dependencies of melti ng zone and rain components; and (iv) contributions from widespread an d showery rain. The method has been tested using 21 years of data cove ring the 11-30 GHz range and shows good agreement. Finally, contour ma ps of link availabilities are presented for a hypothetical 20/30 GHz s atellite at 6-degrees West.