Double Dipole Antenna SIS Receivers at Frequencies above 500 GHz

Resonances of simple tuning circuits up to 1 THz coupled to SIS tunnel junctions were obtained by means of FTS measurements and compared with calculations based on the Mattis-Bardeen theory. We developed a new sort of devices for frequencies above 700 GHz using gold instead of Nb for the if-parts. First measurements of the video and heterodyne response of all-Nb SIS receivers have been made at frequencies between 720 and 890 GHz. We measured a possible heterodyne response of 1.1 dB due to a hot/cold load at 830 GHz. The video response of the unpumped junction was 0.3 dB due to the hot/cold load.