Alignment and compensation method for large-scale reflector antennas based on laser tracker considering thermal deformation effects

Abstract

The performance of a large-scale compact antenna test range (CATR) critically depends on the surface accuracy of its reflector. However, during on-site alignment lasting for several weeks, temperature variations induce thermal deformation in both the reflector and the measurement system, leading to drift in the laser tracker’s measurement coordinate system and resulting in cumulative alignment errors. To address this challenge, this study proposes a compensation method for reflector antennas alignment that accounts for thermal deformation. By selecting fiducial holes on central panel as reference points, it embeds anisotropic thermal deformation coefficients into a numerically solvable formulation, enabling effective correction of coordinate drift. Its effectiveness was verified through an engineering case involving a large CATR reflector with an overall size of 14 m × 13.1 m. Measurement results show that the proposed method reduces alignment error by approximately 80%, and improves compensation accuracy by roughly a factor of two compared with the direct singular value decomposition method. The entire reflector was successfully aligned achieving a final root-mean-square surface error of 0.027 mm across all rectangular panels. This study demonstrates that the proposed thermal deformation compensation method effectively mitigates environmental fluctuations during long-term alignment process, significantly enhancing both the alignment precision and efficiency of large CATR reflectors in practical engineering applications.