Successful implementation of satellite systems in the World Administrative Radio Conference for the Planning of the Broadcasting-Satellite Service (Geneva, 1977) (WARC BS-77) and the First Session of the World Administrative Radio Conference on the Use of the Geostationary-Satellite Orbit and the Planning of the Space Services Utilizing It (WARC ORB-85) broadcasting-satellite service (BSS) plans is dependent upon accurate calculation of mutual interference between satellite networks. Earth-station transmitter (up link) the concept of an equivalent gain for each partial link may be employed. There are two antennas involved in each partial link, and these have both co-polar and cross-polar transmission and reception characteristics. In addition, atmospheric propagation effects, represented principally by co-polar attenuation and cross-polar discrimination, influence the net signal level.