Active optimization adjustment for the surface accuracy of spaceborne SAR antennas

Abstract

Inevitable disturbances in the spatial thermal environment will seriously degrade the surface accuracy of satellite antennas. Unfortunately, the ground pre-adjustment cannot adaptively guarantee the antenna performance under alternating thermal loadings. To tackle the challenge, this study proposes an active optimization adjustment method to achieve the required surface accuracy for spaceborne antennas. Starting from the comprehensive analysis of external thermal fluxes in outer space, the heat transfer model is firstly established to acquire the temperature field of the antenna system. Subsequently, considering the thermoelastic effect and the geometrical nonlinearity, the antenna surface accuracy is predicted. In particular, the thermoelastic forces induced from temperature changes and dimensional deviations are precisely determined by the absolute nodal coordinate formulation. Moreover, an efficient computational method with invariant matrices is developed to accelerate the prediction. On this basis, we construct the on-orbit active adjustment model to compensate for the effect of thermally induced deformation on the surface accuracy. A mixed-variable optimization algorithm is further put forward to find the optimal strategy of dimensional adjustment. Finally, a case study with simulation analysis and experiment verification demonstrates the feasibility and superiority of the proposed surface adjustment method.