Abstract.In order to ensure higher accuracy and better electrical performance of large antennas in future,this paper does some research for deformation of antenna’s reflector:modeling for 25m antenna and reappearing deformation when elevation changes every 15° just considering gravity by using ANSYS.Using results of simulation obtains deformation error curves with elevation changes, creates the conditions for compensating distortion and has a certain value. By using Ruze formula, deeply studies the regular about antenna’s electrical performance influenced by deformation because of elevation changes,obtains meaningful data and tables of relationship between elevation and parameters of electrical performance in nine bands of 25m antenna.It finds out that when working in high-frequency band, efficiency and gain loss of antenna will be more affected by elevation angle changes.Finally creates conditions for optimizing antenna parameters and performing high reliability tasks such as deep space exploration and aerospace communication.

The pointing of an antenna always exists deviation due to track deformation, gravity and thermal influence. Through long time observation, we find that sunlight also has some influence on antenna structure. In order to get the antenna pointing deviation in the effects of the sunlight of 25m antenna in Urumqi, we use the frame-typed level and thermometer to make a week’s measurement about the temperature around the antenna and the antenna tilt. The measured data was analyzed and combined with the track deformation data, and the pointing error fixed model as well as the thermal load deformation model were built. The measured data was fitted by the two models, and the result shows that the model can well reflect the pointing error and thermal load error, thus can give a better understanding of the antenna deformation, and also can give some good reference to antenna pointing calibration and the antenna’s reconstruction.