Progress on tunerless SIS mixers for the 200-300 GHz band

An integrated superconductor-insulator-superconductor (SIS) mixer for the 200-300-GHz band with no adjustable tuning is described. A waveguide input is coupled to a coplanar mixer circuit with six individually tuned SIS junctions in series. Using the best mixer, the receiver noise temperature is 45-80 K DSB over 215-275 GHz. The mixer noise temperature at 230 GHz is 12 K DSB, and the conversion loss is 2.5 dB DSB.<
>