FANATIC - AN SIS RADIOMETER FOR RADIO ASTRONOMY FROM 660 TO 695 GHZ

FANATIC is a compact radiometer optimized for radio astronomy from about 660 to 695 GHz (lambdalambda 455 - 432 mum). We observed a large number of molecular and atomic spectral lines from galactic and extragalactic sources during FANATIC's first run on the James Clerk Maxwell Telescope in early March 1994. Double sideband receiver temperatures during observations were about 800 K (25 hnu/k). The heart of the receiver is a two-junction Nb/AlO(x)/Nb SIS array fed by a sandwiched V-Antenna. The junction array and antenna are fabricated together at IRAM's Grenoble SIS laboratory. Each junction has a normal resistance of R(n) approximately 10 OMEGA, an area of approximately 2 mum2, an individual radial stub circuit to resonate the capacitance, and a lambda/4 transformer to match to the antenna. The solid-state local oscillator is a mm-wave Gunn oscillator followed by a doubler and tripler. The LO diplexer is a Martin-Puplett interferometer, which insures that there is always abundant LO power for operation and speedy tuning. The receiver and telescope coupling optics, LO, dewar, and calibration system fit on an 0.6 x 0.8 m optical breadboard.