ASI regulations comparison for GSO satellite communication system at Ku-band

Very small aperture terminal (VSAT) at Ku-band is very attractive in complex terrestrial and marine environment of military or disaster scene. The small aperture antenna characteristic of VSAT leads to strong interference to adjacent satellite systems. This situation is severely aggravated as Geostationary Satellite Orbit (GSO) becomes extremely congested. Various national and international agencies have imposed regulations on VSAT adjacent satellite interference (ASI). One regulation, called ΔT /T method, is used for accessing the necessity of ASI coordination, which is sophisticated and inconvenient to carry out. Another regulation imposed limit on off-axis effective isotropic radiated power (EIRP) of terminal, and specified the maximum allowable off-axis EIRP spectral density (OESD). This paper described and analyzed the salient features of these ASI regulations. Upon demonstration of their compatible and complementary relationships, it is shown that the simpler EIRP rule can be an alternative for the more complex ΔT/T method for ultra-small terminals (USAT). In this way, it will help reduce the complexity of the coordination determining procedure.