Abstract: From the viewpoint of tracking strategies and link establishment, this paper studies the space geometrical relationship between a TDRS and user satellites in detail. Taking into account of the occultation caused by the Earth and the body of a satellite, the bidirectional tracking rules for a TDRS and user satellites are investigated based on classical orbital elements and the satellite's attitude. The coverage of a TDRS over a user satellite with different orbital altitudes is calculated and simulated. In order to overcome the occultation caused by the body of a user satellite, a way to fix the antenna to a mast which extrudes above the side towards space of a user satellite is presented. With an appropriate height of the mast, the occultation can be eliminated. All these formulas and strategies are the key elements for TT&C and applications of China's future TDRS.

Key words: TDRS, use satellite, coverage, antenna installation