Analysis of Antenna Pointing Error for Ground-Based Radar Lunar Imaging

The accurate mapping of the lunar surface is crucial for future missions, yet ground-based (GB) radar system faces challenges due to antenna pointing error. This paper investigates the pointing error in GB radar antennas used for lunar surface imaging. To begin with, the systematic errors in GB radar system are analyzed, and empirical error models for both elevation and azimuth angles are established. Based on these error models, an antenna pointing error model is developed, an echo signal amplitude loss model is then formulated for analysis. Simulations demonstrate the time-varying of this error and its impact on image quality. The impact on the imaging quality is minor, yet specific directions exhibit more pronounced degradation, particularly in the Y-axis, with more noticeable degradation in Peak-Side-Lobe Ratio (PSLR) and Integrated-Side-Lobe Ratio (ISLR).