Precise Control of Beam Formation for Mobile Communication Satellites Based on On-board Measurements of the Shape of the Large Reflector Surface

Abstract

To achieve high throughput to effectively accommodate users, multi-beam systems reusing several frequency bands with small beams are effective. Using a reflector antenna with a very large aperture on the satellite is a promising option for next-generation mobile communication satellites for small user terminals with small beams. A deployable reflector is a flexible structure instead of the hard dish reflector. To improve the electrical performance of the antenna and avoid performance deterioration caused by aberration, the parabolic reflector must be accurately shaped. We propose continuous beam stabilization by optimizing the parameters for the phased array. If the reflector shape can be measured precisely while in orbit, the beam pattern and antenna performance can be corrected continuously by updating the excitation parameters based on the measured reflector shape with a brief time delay. For the proposed algorithm to perform antenna-pattern stabilization effectively, the shape of the reflector surface should properly determine the optimized phased array parameters to compensate for the deterioration of the antenna pattern. The objective of this study is to confirm the feasibility of the approach to beam pattern correction. The simulations of deformed reflector surfaces deteriorating the antenna pattern reveal that the application of optimized phased array parameters for the reflector shape can compensate for the deformation and recover the antenna pattern.