BROAD BAND MM WAVE SIS RECEIVERS FOR RADIO ASTRONOMY

RESEARCHERS ARE DEVELOPING MM WAVE SIS HETERODYNE RECEIVERS INTEGRATED WITH ON CHIP LOCAL OSCILLATORS FOR USE IN RADIO ASTRONOMY. THE RECEIVERS INCORPORATE SUPERCONDUCTING TUNNEL JUNCTIONS (SIS JUNCTIONS) AS THE MIXING ELEMENTS, TOGETHER WITH JOSEPHSON JUNCTION LOCAL OSCILLATORS, TO PROVIDE MIXING IN THE 50-700 GHZ FREQUENCY BAND. LOCAL OSCILLATORS BASED ON THE AC JOSEPHSON EFFECT HAVE DEMONSTRATED OPERATION UP TO FREQUENCIES IN EXCESS OF THE SUPERCONDUCTING TUNNEL JUNCTION GAP FREQUENCY, ABOUT 1.5 THZ FOR NB AND 3 THZ FOR NBN(1). THESE OSCILLATORS MAY BE TUNED ELECTRICALLY, ARE EXTREMELY COMPACT, AND DISSIPATE SMALL AMOUNTS OF POWER. INVESTIGATORS HAVE FABRICATED JOSEPHSON JUNCTION ARRAY OSCILLATORS FROM WHICH THEY HAVE COUPLED OVER 125 NW INTO A 10 LOAD AT 105 GHZ. THESE OSCILLATORS AND THE RESEARCHERS' PROVEN PROCESSING CAPABILITY AND SUPERCONDUCTING CIRCUIT DESIGN EXPERTISE ARE USED TO PRODUCE MONOLITHIC MILLIMETER/SUBMILLIMETER WAVE HETERODYNE RECEIVERS. THESE RECEIVERS HAVE INTRINSIC UTILITY FOR RADIO ASTRONOMY, AND WOULD HAVE APPLICATION IN ADVANCED COMMUNICATION AND RADAR SYSTEMS, AS WELL.