Compensation for gravity deformation via subreflector motion of 65 m shaped cassegrain antenna

Compensation for degrading electromagnetic performances is one of the most important concerns for engineers involved in the structural design of a large antenna. A method is proposed to compensate the degrading electromagnetic performances induced by the main reflector deformation of the large and shaped Cassegrain antenna by adjusting the subreflector position in real time. Segmented parabola fitting based on the least squares method of the theoretical discrete data of the main shaped reflector yields a standard group of parabolic torus that is later used to fit the deformed main reflector, with all the parabolic toruses confocal in the fitting. The optimised best-fit parameters and the matching between the main reflector and subreflector calculate the adjustment quantity of the subreflector. The adjustment quantities, stored in the database of the subreflector, working under various conditions can be called in real time to compensate the gravity deformation of the main reflector. The application of the method to a 65 m aperture-reflector antenna was successful, thus, laying a good foundation for its application in engineering practice.