A High-Pointing-Accuracy Implementation Method for an 18-m Antenna Based on a Multi-Error-Source Coupled Model

High-frequency VLBI (Very Long Baseline Interferometry) observations impose stringent requirements on antenna pointing accuracy. This paper proposes a high-precision pointing implementation method that integrates a multi-error-source coupled model with hierarchical compensation. Taking an 18-m antenna as the object of study, the influence of gravity is quantified through structural-electromagnetic coupled simulation, establishing a unified model encompassing geometric, random, environmental, and dynamic errors. Using the 95% confidence bound (defined as 1.96σ for each error component) and the RSS (Root Sum of Squares) synthesis method, the budgeted system pointing error is estimated to be 8.64 arcseconds (at 40 GHz). An innovative three-level compensation system of "mechanical adjustment-model calibration-active suppression" is constructed, clarifying the mapping relationship between error sources and the TPOINT (Telescope POINT) model. To validate the proposed approach, actual radio source tracking experiments were conducted on the 18-m antenna. The experimental results demonstrate that after applying the three-level compensation strategy, the residual pointing error is reduced to approximately 7.9″ (RMS@95%), which agrees well with the theoretical budget of 8.64″. This method provides a systematic solution for the precision design and engineering implementation of high-frequency antennas, with the effectiveness confirmed through both theoretical budgeting and experimental validation.