A 110 GHz superconductor insulator superconductor (SIS) tunnel junction receiver has been developed and used in regular astronomical observations on the 4m radio telescope at the Department of Astrophysics, Nagoya University. The SIS junction consists of a sandwich structure of Nb/AlOx/Nb, and is cooled to 4.2K with a closed cycle He-gas refrigerator. The receiver exhibits a best double side band noise temperature of 17±2 K at 110GHz. The receiver has a good response over this input frequency range of 98-115 GHz.
"A 100 - 115 GHz SIS receiver for radio astronomy", Proc. SPIE 1576, 16th International Conference on Infrared and Millimeter Waves, 15761V (1 October 1991); doi: 10.1117/12.2297780; https://doi.org/10.1117/12.2297780