On-Orbit Demonstration of a Deployable Ka-Band 16-Element Active Phased-Array Transmitter

This paper presents an on-orbit demonstration of a deployable Ka-band 16-element active phased-array transmitter onboard the RAISE-4 small satellite in a 540 km low Earth orbit. Beam steering was successfully achieved independently by each transmitter module and simultaneously by both modules, demonstrating coherent multi-transmitter operation in space. Phase calibration, previously proposed and validated through ground experiments, was successfully demonstrated in orbit to compensate for structural deformation of the deployable membrane, enabling effective beamforming under non-planar conditions. In addition, transmitter module temperatures were monitored during the mission, and a clear correlation between transmitter temperature and received signal gain was observed, demonstrating the impact of thermal conditions on RF performance in orbit.