INMARSAT second generation satellites for mobile communications

The second-generation satellites of INMARSAT (International Maritime Satellite Organization) are in the final stage of integration and testing. The satellites will satisfy the needs originated by the rapid expansion of the system and will allow the introduction of new mobile communications services. The authors outline the essentials of the spacecraft design and the types of services that will be provided using the new satellites; in particular, they consider the characteristics of the communications transponder, its design and technology, the requirements and the design solutions, and the most significant communications parameters. Paralleled linearized traveling-wave amplifiers, L-band shaped global direct radiating array antennas, and surface-acoustic-wave channelization filters are being implemented in the system. Passive intermodulation product generation and multipaction are being recognized as design drivers.<>