Electronic Resource
Springer
International journal of infrared and millimeter waves
14 (1993), S. 1867-1887
ISSN:
1572-9559
Keywords:
Quasioptical SIS mixers
;
submillimeter radiometers
;
radio astronomy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract We report the development of a low noise heterodyne receiver optimized for astronomical observations in the 650 GHz atmospheric window, and specifically for the CO(J=6→5) line at 691.5 GHz. The system is based on an open structure SIS heterodyne mixer pumped by a continuously tunable solid state oscillator. A niobium SIS junction double array is placed at the end of an integrated V-Antenna. For broad band impedance matching a combination of microstrip impedance transformer and radial stub was used. Receiver noise temperatures of 550 K DSB at 684 GHz were achieved at a 1.8 K physical temperature. The performance improved substantially when decreasing the temperature from 4.2 to 1.8 K. Comparison of model calculations and Fourier transform direct detection measurements of the tuning structure implies that this effect is likely due to the coincidence of operational frequency and the gap frequency of the niobium.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02096361
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