Measurement of a large deployable antenna for radio astronomy in space

A large radio astronomy antenna on Halca satellite was deployed in 1997 in space. The main reflector with the maximum diameter of 10 m is composed in a novel deployment scheme of tension truss as shown. The operating frequencies are 1.66 GHz (L-band), 4.85 GHz (C-band) and 22.15 GHz (Ka-band), all protected for radio astronomy use. If a mast is not completely extended, the reflector antenna suffers from a systematic phase error in the area between its neighboring masts. The exposure of cables to space environment and the heat by the solar radiation may also originate a phase error in the aperture. The antenna gain of the main lobe was measured using compact radio stars. The feed loss was derived from noise temperature measurements. As for the near axis radiation patterns, the artificial satellite Himawari in orbit was used as a wave source for verification purpose though the frequency is limited in L-band. This paper describes the measurement methods of the antenna and results except for the radiation pattern measurement. The consequent evaluation of the antenna is also given.