Superconductive hot-electron-bolometer mixer receiver for 800-GHz operation

In this paper, we describe a superconductive hot-electron-bolometer mixer r eceiver designed to operate in the partially transmissive 350-mu m atmosphe ric window. The receiver employs an NbN thin-film microbridge as the mixer element, in which the main cooling mechanism of the hot electrons is throug h electron-phonon interaction. At a local-oscillator frequency of 808 GHz, the measured double-sideband receiver noise temperature is T-RX = 970 K, ac ross a 1-GHz intermediate-frequency bandwidth centered at 1.8 GHz, We have measured the linearity of the receiver and the amount of local-oscillator p ower incident on the mixer for optimal operation, which is P-LO approximate to 1 mu W. This receiver was used in making observations as a facility ins trument at the Heinrich Hertz Telescope, Mt, Graham, AZ, during the 1998-19 99 winter observing season.