Global predictions of slant path attenuation on earth-space links at EHF

Experience gained using the Italian Space Agency (ASI) satellite, ITALSAT F1, has shown that there is a need to account for attenuation caused by cloud and gases in the atmosphere when transmission frequencies above ∼ 30 GHz are employed. This paper describes a method that has been developed to predict attenuation caused by rain, cloud and gas. By using this method, attenuation levels to the closest of five geostationary satellites have been predicted for a link frequency of 39.6 GHz and maps showing global predictions of slant path attenuation that would be exceeded for 10, 5, 2 and 1 per cent of the time are presented. Comparisons between attenuation predictions and measurements collected from beacons carried on the ITALSAT F1 & ACTS satellites are made to establish the validity of the predictions.