Configurations for EHF Satellite Communications for Mobile Users

Abstract

Two-way electronic communications to mobile platforms was initially provided in the HF (3-30 MHz) band. Then, as electronics technology progressed and requirements for increased link availability and capacity emerged, service evolved into the VHF (30-300 MHz), UHF (0.300-3 GHz), and SHF bands (3-30 GHz), with the latter two often involving satellite-based systems. Recently, considerable consideration has been given to utilizing satellite communications systems operating in the allocated EHF (30-300 GHz) bands to provide wide-area coverage, to overcome frequency congestion difficulties, and to provide sufficient bandwidth for projected capacity increases and for interference protection via spread-spectrum modulation techniques. By using emerging spacecraft technologies such as multiple uplink antenna beams, onboard signal processing, and downlink beamhopping, EHF systems can be configured to serve large numbers of small, mobile users. The resulting satellites would be of modest-size, and the associated limited-size user terminals would be less expensive and easier to install and maintain than those for EHF systems which only employ conventional technology. This paper describes several system configuration which use one or more of the above technologies, discusses the advantages of each, and indicates possible spacecraft and terminal implementations.