Abstract: This paper describes a mechanically despun satellite antenna system for the domestic telecommunication service. The antenna system consists of three parts: an assembly of the omnidirectional telemetry and command antennas, a directive communications antenna and a three channel noncontacting rotary joint. The telemetry and command antennas are antennas, the radiation patterns of which are omnidirectional patterns with the circular polarization. The directive communications antenna is a offset elliptical paraboloid antenna with single horn feed for both transmiting and receiving. A 5°×8° elliptical beam radiated by the paraboloid antenna provides proper coverage over China's mainland. The three channel noncontacting rotary joint is a concentric three coaxial line configuration, which forms three transmission channels. There are chokes at the rotary join of each coaxial line. The channel insertion losses of the rotary joint are 0.6～0.8dB. The isolations between the channels are greater than 50dB.