Cryogenic dual-temperature low noise amplifier in K band

Future ground stations will require a high level of operational flexibility and, for this reason, the possibility to adjust their receiving performance (i.e. signal-over-noise) is beneficial. This study presents an approach to achieve this flexibility based on a dual-temperature low-noise amplifier, which can be normally operated at room temperature (300 K), reducing the operational and maintenance costs, and at cryogenic temperature (103 K) only when required, for example, for critical mission supports. To demonstrate the effectiveness of this solution, a dual-temperature K-band low-noise amplifier is designed, manufactured and measured for the first time. Critical aspects, such as the stability of the electromagnetic response over the entire temperature range, and the reduction of the thermal load from the entire assembly, fundamental for a fast transition between room and cryogenic temperatures, are discussed. In particular, the low-noise amplifier exhibits a minimum gain of 20 dB over the entire working bandwidth (18-22 GHz) and a maximum noise figure of 2.2 at 300 K and 1.4 at 103 K, with a transition time between room and cryogenic temperature of <120 min because of a total thermal load lower than 1 W.