Cost Considerations for EHF Satellite Communications User Terminals

Abstract

Mobile satellite communications at UHF have gained wide acceptance in the past several years. This acceptance has been largely a result of the improvement in communication reliability over other long-range systems such as HF. Deficiencies, however, have been noted with respect to the performance of UHF satellite communication (SATCOM) systems where anti-jam (AJ) or low probability of intercept (LPI) characteristics are of importance. Recent advancements in technology coupled with increased requirements for improved AJ and LPI have focused attention on the EHF frequency range for evolutionary replacement and/or augmentation of UHF SATCOM systems. RF equipment in this frequency range has the potential for the implementation of highly compact terminals for mobile application such as required for airborne force elements. In the next 5-10 years, a wide range of technologies will be applied to the development of EHF user terminals. Critical trade-offs exist between satellite and terminal complexity as well as within the terminal itself. Within the terminal, antenna gain versus HPA power, antenna mounted solid-state PA's versus TWT PA's, phased arrays versus advanced reflector antennas all must be considered. Although the antenna and HPA are the most significant cost drivers, secondary trade-offs, such as antenna gain versus use of paramps or FET's, and synthesizer approaches for fast hop and signal processing implementation also must be addressed. This paper addresses a typical terminal for a small mobile user such as an airborne force terminal. Typical system and spacecraft characteristics are defined and tradeoffs carried out on a parametric basis between various terminal elements to establish cost-performance relationships.