A 125-180 GHz fixed-tuned SIS mixer for radioastronomy

• Published in: IEEE transactions on applied superconductivity 1997-06, Vol.7 (2), p.1073-1076
• Main Authors: Karpov, A., Blondel, J., Pasturel, P., Gundlach, K.H.
• Format: Article
• Language: English
• Subjects: Applied sciences; Astronomical and space-research instrumentation; Astronomy; Circuit noise; Circuit properties; Conductors; Current distribution; Earth, ocean, space; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations; Magnetic field measurement; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Power cables; Radio telescopes and instrumentation; heterodyne receivers; Superconducting cables; Superconducting device noise; Superconducting devices; Superconducting transmission lines; Testing
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/77.614710

An ultra low noise fixed-tuned SIS mixer covering an instantaneous band of 45% around 150 GHz has been developed for radioastronomy. A new type of coplanar tuning circuit for the SIS junction is introduced. The Nb/Al oxide/Nb junctions are 2 /spl mu/m/sup 2/ with critical Josephson current density of 4.2 KA/cm/sup 2/. The minimum DSB mixer noise is 11 K. The minimum DSB receiver noise is 19 K, while the average noise is 25 K in the 130-175 GHz range with a 1 GHz IF band. A speedup of the observations by a factor 2-3 is possible with the new receiver at 30 m IRAM radiotelescope.