A 22 GHz receiver with high phase stability for radioastron space-VLBI-mission

A space-qualified low-noise 22 GHz receiver for the international space-VLBI mission Radioastron has been constructed. The microwave electronics is realized by using thermally matched hybrid circuits. The most important properties of the receiver are phase stability, sensitivity and reliability. The high sensitivity is due to a cooled low noise HEMT amplifier (LNA). The measured receiver noise temperature is less than 100 K. The phase stability is achieved by compact structure and thermal stabilization. Phase stabilities of better than 0.13°/°C and 0.2°/°C for the receiver and the LNA units are measured, respectively. The calculated reliability of the receiver exceeds the requirement of 0.97 for the three year mission.