Efforts toward Transmission Experiments Utilizing Transponder of 21-GHz Band on Broadcasting Satellite

Abstract

The broadcasting satellite BSAT-4a was successfully launched on September 30th, 2017 (JST). BSAT-4a has a 21GHz-band experimental transponder in addition to the 12-GHz-band broadcasting transponders using right- and left-hand circular polarization. We are planning to use the 21-GHz-band transponder for various experiments, for example, on wideband-transmission and rain-attenuation measurement. As one of the efforts toward the experiments, we fabricated a 21-GHz-band receiving antenna with a 1.5 m parabolic reflector. The receiving frequency is 21.4 to 22.0 GHz and the polarizations are right- and left-hand circular polarization. Measured results showed that the antenna gain and cross-polarization discrimination were more than 48 dBi and 32 dB, respectively. We also confirmed that the fabricated antenna satisfied the reference pattern of Rec. ITU-R BO.1900.