TWTAs for Satellite communications: Past, present and future

Downlink amplifiers on geostationary communications satellites are required to operate in harsh environments for extended mission lifetimes (of up to 20 years) with a challenging combination of performance parameters and ultra-high reliability. TWTAs were the only option for systems designers nearly 50 years ago at the birth of the space age that were capable of providing the required power/frequency product for communications links. This history is similar to that of many other applications (radar, ECM, etc.). More recent history, however, shows that satellite communications payload architecture continues to use TWTAs for the vast majority of downlink amplifier applications while many other types of systems have moved away from TWTAs into alternate amplifier types and/or architectures. This presentation will highlight many of the key differentiating capabilities of modern space qualified TWTAs that have enabled them to maintain and grow a competitive advantage versus solidstate amplifier in satellite communications payloads. These differences are worth noting by designers of all types of systems requiring microwave amplification.