I. Introduction
Space-borne antennas are mainly used for signal transmission between satellites and the ground. The long transmission distance requires accurate beam pointing of space-borne antennas. Beam pointing error results in the failure of the signal transmission mission. Due to the global and local deterioration, the beam pointing error greatly affects the communication [1]. Deformations on the antenna reflector surface will occur because of extreme temperature, microgravity environment and repeated deployment and so on [2]. All these errors will affect the beam performance, and accordingly the focal plane field will also change. What's more, with the operating frequency increasing, this negative effect will be more remarkable.