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This paper presents a progress summary of NASA's efforts in developing 20 and 30 GHz GaAs MIC devices and an advanced satellite communications antenna system using these devices. In the interest of preserving resources such as frequency spectrum and orbital space the antenna system is being developed with multiple fixed spot beams and multiple scanning spot beams.NASA set high goals for the MMIC development to push GaAs technology. These goals and the main features of tne MMIC devices are discussed. Some packaging and characterization considerations are also discussed.Tne 20 GHz transmit antenna and 30 GHz receive antenna are being developed separately. Tne approach selected is to perform contractual configuration studies, purchase a 20-GHz experimental antenna system (EAS) and perform in-house evaluation.Tne features and key specifications of tne EAS are discussed. Additional supporting technologies such as effects of coupling on modest sized arrays, MMIC matching techniques, in-house uialytical capability, wideband and dual frequency microstrip patch array development, and MMIC packaging techniques are described.Some plans for future work are also discussed.

Future versions of data relay satellite systems are currently being planned by NASA. Being given consideration for implementation are on‐board digital beam‐forming techniques which will allow multiple users to simultaneously access a single S‐band phased array antenna system. To investigate the potential performance of such a system, a laboratory simulator has been developed at NASA's Lewis Research Center. This paper describes the system simulator, and in particular, the requirements, design and performance of a key subsystem, the phased array antenna simulator, which provides realistic inputs to the digital processor including multiple signals, noise and non‐linearities.

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