Thermal Deformation Measurement of Onboard Antenna Reflector in Thermal Vacuum Chamber by Photogrammetry

A multibeam antenna system for WINDS, a giga bit class satellite, has been developed. The antenna system and its main reflectors have been confirmed to satisfy structural requirements. In addition to the structural requirements, each beam of the antenna system needs to satisfy RF requirements such as peak gain and inter-beam isolation. However, thermal deformations of the reflectors during orbit affect the antenna system’s RF performance. Furthermore, in the case of multibeam antenna systems, the RF performance varies more unpredictably than that of single beam antenna systems. In order to be precise in the prediction of RF performance, we need to know the accurate thermal deformation of the reflector in orbit. To this end, we conducted a thermal deformation measurement test using photogrammetry in the JAXA space chamber to make accurate structural analysis models that would enable us to predict this RF performance. From the test result, we obtained a model with greater precision than prior to the measurement test.