A 492 GHz quasioptical superconductor-insulator-superconductor (SIS) heterodyne receiver for submillimeter astronomy has been constructed with a double-sideband noise temperature of 170±25 K, where the system response is an average over a 600 MHz i.f. bandwidth centered at 1.5 GHz. The excellent sensitivity is achieved through use of a planar twin-slot antenna feeding a pair of Nb–Al2O3–Nb junctions linked by an inductance. A main beam of f/15 has been measured. The performance of this receiver is comparable to that of the best 492 GHz waveguide receivers currently in operation
