System Considerations for Millimeter Wave Satellite Communications

The feasibility of instrumenting earth-space and satellite-satellite links is analyzed for frequencies between 30 and 100 GHz. Propagation and orbital parameters are considered, and data (mainly from computer programs) are presented on time-in-view for various ground locations, mutual visibility time between two orbiting satellites, effects of limiting the antenna elevation angle excursion, antenna pointing considerations, antenna types and gain/beamwidth limitations, and available ground station facilities. Orbits range from 100 to 19,357 nautical miles (nmi) altitude (synchronous) and from O° (equatorial) to 90° (polar) inclination angles. System design parameters are tabulated for typical links, including transmitter power requirements, doppler shifts, tradeoffs in bandwidth, range, power, and antenna gains. The millimeter wave equipment situation is reviewed because any space system will be limited by the state-of-the-art in hardware and techniques, including performance, reliability, weight, space, and power requirements.