Effect of Antenna Drives on Attitude Control Systems

Abstract

Accurate antenna pointing control is one of the key technologies in developing a multibeam communications satellite. This paper describes evaluations of the coupling of an antenna pointing control system consisting of a satellite attitude control loop and an antenna drive control loop. The evaluation of coupling between two loops is a significant problem in satisfying accuracy requirements of the system with large antennas and flexible solar paddles.
First, the coupling factor was formulated from the dynamics of the 3-axis stabilized satellite with antennas and solar paddles. Second, values of the coupling factors of a 2-ton class satellite were calculated for two antenna drive methods. The results confirm that the coupling factor mainly depends on the paddle structural characteristics, moments of inertia of antenna reflectors and the ratio of the beam angle to the antenna drive angle.