Research and development for international satellite communications in Japan

Major research and development activities for international satellite communications in Japan are introduced. Countermeasures against heavy rainfall-induced deterioration of communications signals, particularly for satellites above the Indian ocean, are addressed. These include results of studies on depolarization compensation for dual-polarized waves, and of a series of propagation experiments for determining the rain attenuation characteristics at 11 GHz for propagation paths with low-elevation angles. A new antenna and linearizer for earth station facilities are briefly described. A new TDMA system is described along with new maritime satellite communications systems. Computer programs developed as tools for optimizing satellite communications systems are listed, giving their purpose, functions, and intended ministries and programs.