Ultra-stable Peltier-cooled low-noise 3-mm-wave-band receiver

Such features as the highest sensitivity and stability are characteristic of SIS/HEMT cryogenically cooled receivers being used in radioastronomy, while the "conventional" superheterodyne receiver based on a Schottky-diode mixer and GaAs FET IF-amplifier, is preferred as a general-purpose device. This paper briefly describes a design technique for upgrading a "worn" (i.e. cryogenics-free) receiver from the radiometric standpoint: improvement in noise and stability performances. The specific device has been designed for the highly promising 3-mm band. The full-height waveguide whisker contacted mixer (DSB conversion loss no more than 2.1 dB over 85-115 GHz) and ultra-low-noise FET preamplifier (NF close to 0.5dB, operation band 1.2-1.7GHz) are similar to that described previously. An added reduction of the receiver noise temperature (DSB Tn is about 250 K) has come about through moderate (to -75°C) cooling of the mixer/IF-amplifier only by a 3-stage semiconductor Peltier cooler. As far as could be determined from the literature, 250 K is the best value for non-cryogenic receivers in the appropriate frequency band