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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 379-382 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A K-band receiver using cooled high-electron mobility-transistor (HEMT) amplifiers was developed at the Nobeyama Radio Observatory (NRO). Remarkable reduction of receiver noise temperature Trec was obtained when it was cooled down to cryogenic temperature. The lowest Trec of 75 K was obtained at 23.4 GHz. This low noise characteristic reveals that the cooled HEMT amplifier is promising as a sensitive receiver for radio astronomical observations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 382 (1996), S. 426-428 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] BR1202 - 0725 was found in an optical multi-colour based search15 and is the third-highest-redshift quasar known to date. Subsequent submillimetre observations16'17 revealed significant dust thermal emission towards this object. The amount of dust was estimated to be 109M(: assuming a dust ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 14 (1993), S. 1251-1271 
    ISSN: 1572-9559
    Keywords: Radio Astronomy ; Receiver ; SIS ; Tunerless Mixer Mount
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have developed a 100 GHz band SIS receiver using a simple mixer mount design, which does not use variable RF tuning elements, such as a back short tuner or an E-plane tuner. The mixer mount structure was designed using calculations of the embedding impedance of the mixer mount, and of receiver performance, using the quantum theory of mixing under the 3-port approximation. The mixer mount structure we designed has a 1/7 reduced height waveguide and a “back short cavity”. We have constructed a receiver system using this tunerless mixer mount design, and we have measured the receiver noise temperatures for two different tunerless mixer mounts using arrays of four Nb/Al-AlOx/Nb junctions. For one of the two mixer mounts, we obtained very low noise receiver temperatures, 35–70 K, over the very wide frequency range of 80–120 GHz. We also show that, due to IF missmatching, the noise of the IF amplifier is the main contributor to the receiver noise temperature. We also compared the results of measurements with the results of our theoretical calculations. Our calculations reproduced the tendency of receiver performances very well. This tunerless mixer mount has application on the MM-Wave Array and in the multi-beam receiver.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 8 (1987), S. 1-11 
    ISSN: 1572-9559
    Keywords: millimeter wave receiver ; SIS junctions ; mixer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A 40 GHz band SIS mixer receiver has been built using Nb/Al−AlOx/Nb array junctions and a 4.3 K closed cycle helium refrigerator. The minimum conversion loss of the mixer is 2±1 dB and the single sideband receiver noise temperature (TRX (SSB)) is as low as 110±10 K at 36 GHz. TRX (SSB) is almost constant in the IF bandwidth of 600 MHz. The mixer saturation level is as high as 15 nW, which is comparable to the injected LO power.
    Type of Medium: Electronic Resource
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