The mixer mount for a 75 -110 GHz SIS (superconductor-insulator-superconductor) receiver was scale modeled at 2 - 8 GHz . The mixer mount had a 4-step Chebychev single ridge transformer to launch the rf signal from the waveguide to a microstripline circuit. The microstripline circuit coupled the rf signal into the on-chip SIS element. A wire inductor in parallel with the mixer was used to tune out the capacitance of the SIS junction. Both the junction and the inductor had rf grounds provided by 90° radial stubs. In the scale model, a 50 Ω chip resistor in parallel with a 1 pF chip capacitor was used in place of the SIS junction to measure the rf matching properties. The inductor was modeled with a thin copper wire. The VSWR of the entire mount was less than 2.1 : 1 over the frequency band corresponding to 75 - 107 GHz. Receiver measurements with the actual mixer mount employing trilayer SIS tunnel junctions gave similar trends across the band.
D. Winker, D. Winker,
"Design of a w-band SIS mixer", Proc. SPIE 1514, 15th International Conference on Infrared and Millimeter Waves, 15141W (1 December 1990); doi: 10.1117/12.2301478; https://doi.org/10.1117/12.2301478