CHARACTERISTICS OF THE LARGE DEPLOYABLE ANTENNA ABOARD HALCA IN-ORBIT

Halca was proposed and developed in Institute of Space and Astronautical Science (ISAS)for the VLBI Space Observatory Programme (VSOP). It was launched on 12 February 1997,and placed in the orbit with 31-degree inclination to the Earth’s equator with an apogee of21,400 km from the Earth’s surface and a perigee of 560 km, respectively. The antenna was fullydeployed on 28 February 1997[1].The radiation characteristics before the launch were not actually measured in the far eldnor in the near eld[2]. In order to verify the deployed state and design validity, it is necessaryto measure the characteristics in orbit. In this paper, we propose the antenna measurementmethod using radiostars and a geostationary satellite as radiowave sources, and describe themeasurement results in these method.