Performance of a Ka-Band Transponder Breadboard for Deep-Space Applications

This article summarizes the design concepts applied in the development of an advanced Ka-band (34.4 GHz/32 GHz) transponder breadboard for the next generation of space communications systems applications. The selected architecture upgrades the X-band (7.2 GHz/8.4 GHz) deep-space transponder (DST) to provide Ka-band up/Kaand X-band down capability. In addition, it can also be configured to provide X-band up/Kaand X-band down capability. The Ka-band transponder breadboard incorporates several state-of-the-art components, including sampling mixers, a Ka-band dielectric resonator oscillator, and microwave monolithic integrated circuits (MMICs). The MMICs that were tested in the breadboard include upconverters, downconverters, automatic gain control circuits, mixers, phase modulators, and amplifiers. The measured receiver dynamic range, tracking range, acquisition rate, static phase error, and phase jitter characteristics of the Ka-band breadboard interfaced to the advanced engineering model X-band DST are in good agreement with'the expected performance. The results show a receiver tracking threshold of —149 dBm with a dynamic range of 80 dB and a downlink phase jitter of 7-deg rms. The analytical results of phase noise and Allan standard deviation are in good agreement with the experimental results.