Sub-reflector modeling of Shigatse 40-meter radio telescope

In large radio telescopes, precise adjustment of the sub-reflector’s position and orientation can effectively compensate for gravitational deformations in both the main reflector surface and sub-reflector supporting structure. This compensation is crucial for maintaining optimal antenna efficiency and pointing accuracy across the full range of elevation angles. This study focuses on the Shigatse 40-meter radio telescope (RKZ40m), systematically analyzing how sub-reflector adjustments influence antenna gain and beam pointing. We developed a novel scanning-based method to establish a unified tracking model for sub-reflector positioning in both the Z- and Y-axis directions, specifically designed for RKZ40m’s unique adjustment mechanism. The model was implemented using real-time measurement data from the telescope’s enhanced correlator system and sub-reflector control computer, with results cross-validated against finite element simulations. Comprehensive performance tests, conducted by comparing system performance with and without the sub-reflector model, demonstrate significant improvements in antenna efficiency, particularly at extreme elevation angles. In the X-band operational mode, the implemented model achieves and sustains antenna efficiency above 70% throughout the entire elevation range, representing a substantial enhancement to the telescope’s observational capabilities.