Shaped power pattern using an onboard array-fed reflector antenna for advanced direct broadcasting satellites

21-GHz band satellite broadcasting is expected to develop as a large-capacity transmission medium for advanced broadcasts featuring multi-channel and ultra-high-definition TV that uses large display screens. The 21-GHz band, however, suffers from heavy signal attenuation due to rain at a power level about three times that of the 12-GHz band in terms of decibels [Y. Kawaguchi et al., April 2002]. Such attenuation can lower the availability of service significantly. As promising approaches to solve this problem, we are now moving forward with on-board large phased array antennas that will increase radiation power only in areas with rainfall to compensate for rain attenuation [Y. Kawaguchi et al, April 2002; S. Tanaka et al., July 2000; S. Tanaka, Feb. 2002]. This paper describes a mitigation technique for rain attenuation using a large-scale phased array antenna for the 21-GHz band broadcasting satellite system. It also reveals the calculated shaped radiation pattern of a phased array-fed single reflector antenna to investigate the feasibility of a radiation pattern that can compensate for rain attenuation.