Algorithm for Estimating Pointing Error of Large Dual-reflector Antenna

Considering the impact of antenna's deformation coupling on the accuracy of pointing error estimation, an algorithm for estimating pointing error of large dual-reflector antenna is proposed based on geometric optics. A model for estimating pointing error of deformed dual-reflector antenna is deduced by establishing mathematical models for the best-fit paraboloid, the offset sub-reflector, and the feed based on the original coordinate system, calculating the radiation areas of reflector, and determining the weighting factor of pointing error. In order to verify this algorithm, the pointing errors for multiple virtual deformation conditions of a 70 m antenna under construction are estimated by this model, the results of which are compared with the results estimated by Beam Deviation Factor (BDF) algorithm and electromagnetic simulation algorithm. The final results show that the pointing errors estimated by the model are coincident well with the results of electromagnetic simulation algorithm and BDF algorithm, and the proposed algorithm is correct. The algorithm provides a theoretical basis for analyzing the effect of antenna's deformation coupling on the accuracy of pointing error estimation, and improves the accuracy of pointing error estimation for antenna to some degree.