Dynamic Compensation of Deteriorated Antenna Pattern by Deformation of Large Deployable Reflector of Mobile Communication Satellite

摘要

Satellite for next generation mobile satellite communication service with small personal terminal requires onboard antenna with very large aperture reflector because small personal terminal with lower power consumption in ground base requires the large onboard antenna with high gain. However, large deployable reflector deforms in orbit because the reflector is not a solid dish but the flexible structure with fine cable and mesh supported by truss structure. In case of phased array antenna with digital beam former, beam performance and property can be modified with adjustment and optimization of excitation amplitude and excitation phase. Fundamental concept of our proposal is that beam pattern and antenna performance can be compensated with the updated excitation amplitude and excitation phase parameters optimized for the reflector shape measured with vision metrology in orbit time by time. In this report, application of vision metrology measurement to precise measurement of large deployable reflector shape in orbit is discussed. In our previous report based on preliminary study of the application, photogrammetric network by using four cameras with 4 Mega pixels is proposed. The feasibility of our proposed photogrammetric network is studied with bundle adjustment simulation for fictitious parabola reflector with diameter of twenty meters. For feasibility evaluation including expected measurement precision estimate, the results of the experimental measurement for similar size structure to large reflector is reported. From the simulation and the experimental measurement, feasibility of the photogrammetric measurement of reflector surface shape with sufficient precision for antenna pattern compensation has been studied.