Radio System Interference from Geostationary Satellites

Geostationary communications satellites have a potential for causing interference into terrestrial radio relay systems since present INTELSAT satellites as well as a number of U.S. domestic satellites transmit a downlink frequency in the 4 GHz common carrier band. Use has been made of recently measured spatial antenna radiation patterns of the AT&T KS15676 pyramidal horn-reflector antenna to calculate the interference noise into typical U.S. high density 4 GHz radio relay systems. The model employed uses the maximum allowed CCIR flux from the satellites so that the results are conservative since the flux from deployed satellite repeaters is normally below that level. Although certain cases such as east-west oriented existing systems with one or more direct exposures may experience noticeable interference, no significant noise problem is foreseen from this source even when the geostationary orbit is populated as heavily as one communications satellite every 3°.