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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 1164-1164 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 1531-1538 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: WASP2 is a lag correlation spectrometer that is optimized for astronomical heterodyne observations of spectral lines from mid-infrared through centimeter wavelengths. Since the instrument is a wideband microwave spectrum analyzer, its basic technology is well suited to radio astronomy, atmospheric remote sensing, and any other application which requires observations of broad spectral lines. In this specific instrument, eight 16 lag correlator boards form a 128 lag spectrometer with 33 MHz spectral resolution. The spectrometer's present microwave components dominate its gain shape, yielding a spectrometer which covers a useful (6 dB bandwidth) single band of 3600 MHz, from 280 to 3880 MHz. The correlator boards have a 3 dB bandwidth of 4000 MHz, from below 100 MHz to near their aliasing limit of 4200 MHz. WASP2 obtains its wide bandwidth with fully analog high frequency components: the voltage multipliers are transistor circuits and the delays are lengths of microstrip transmission line. WASP2 is simple, compact, requires little power, and integrates stably for many hours. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 395 (1982), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 315 (1985), S. 467-470 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] New infrared and submillimetre spectroscopic measurements of the gas dynamics in the central 10 pc of our Galaxy make a convincing case that the mass distribution at the centre of the Galaxy is more concentrated than a spherical isothermal stellar cluster. The measurements fit a point mass of ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 10 (1989), S. 1371-1376 
    ISSN: 1572-9559
    Keywords: Schottky diode mixers ; submillimeter radiometers ; corner cube mixer structures ; radio astronomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We accurately measured the noise temperature and conversion loss of a cryogenically cooled Schottky diode operating near 800 GHz, using the UCB/MPE Submillimeter Receiver at the James Clerk Maxwell Telescope. The receiver temperature was in the range of the best we now routinely measure, 3150 K (DSB). Without correcting for optical loss or IF mismatch, the raw measurements set upper limits ofT M=2850 K andL M=9.1 dB (DSB), constant over at least a 1 GHz IF band centered at 6.4 GHz with an LO frequency of 803 GHz. Correction for estimated optical coupling and mismatch effects yieldsT M=1600 K andL M=5.5 dB (DSB) for the mixer diode itself. These values indicate that our receiver noise temperature is dominated by the corner cube antenna's optical efficiency and by mixer noise, but not by conversion loss or IF mismatch. The small fractional IF bandwidth, measured mixer IF band flatness from 2 to 8 GHz, and similarly good receiver temperatures at other IF frequencies imply that these values are representative over a range of frequencies near 800 GHz.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 9 (1988), S. 505-520 
    ISSN: 1572-9559
    Keywords: Antennas ; Quasi-Optics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract At frequencies above a few hundred GHz, waveguide mixer blocks become extremely difficult to build, so open structure feeds may be more appropriate. One promising planar antenna structure, which can easily be integrated with SIS junctions, is the sandwiched V-antenna. The antenna is completely enclosed in dielectric by placing it between substrate and superstrate blocks. Using a model scaled to a center frequency of 10 GHz, we investigated the beam pattern as a function of frequency, and measured its dependence on gaps between the super-and substrates. We plan to test the structure at a frequency of 345 GHz and to compare it with waveguide horn antennas for possible use in submillimeter astronomical receivers. The antenna patterns and analysis in this work are substantially more extensive than earlier published results.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 224 (1995), S. 117-120 
    ISSN: 1572-946X
    Keywords: Submm. CO spectroscopy ; YSO ; shocks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report submillimeter CO(6-5) observations around 15 nearby young stellar objects of low mass. The correlation between linewidth and peak temperature indicates shock heating of dense gas, presumably at the origin of molecular outflows.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 9 (1988), S. 231-247 
    ISSN: 1572-9559
    Keywords: Radio Astronomy ; Radio Telescopes ; Submillimeter Techniques ; Quasi-optics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Submillimeter receivers which operate in the highest frequency atmospheric windows must still be mounted on large infrared and optical telescopes. Finding the optimum submillimeter wave illumination for these large telescopes is simplified by their effectively perfect optical surfaces and long focal lengths, but is complicated by telescope optics which have been optimized for non-tapered beams. In order to determine the effects of changing illumination edge taper, we calculated idealized aperture and beam efficiencies for telescopes which are used for submillimeter astronomical observations. The optimum illumination edge taper for the large infrared telescopes is near 10 dB, somewhat less than for classical radio telescopes, and is not very critical as long as it is between 10 and 13 dB. We also present an accurate method for measuring the sizes of, and deviations from, Gaussian beam pattern distributions by using astronomical sources which have sizes comparable with the beam.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 13 (1992), S. 1313-1320 
    ISSN: 1572-9559
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper we describe the design and performance of a variable reflectivity output coupler for optically pumped far infrared (FIR) lasers. The output coupler is a compact, tunable Michelson interferometer. The output coupling ratio (i.e. the Michelson transmission) is adjustable between 0 and ≥60% for laser line wavelengths between 110 and 500 μm. This output coupler provides increased output power and flexibility, since it can be tuned to optimum coupling ratio for different laser lines. Beam profile measurements show that the Michelson output coupler produces a well collimated Gaussian laser beam. Design features are a) the use of 10 μm reflection coated quartz vacuum window which acts as a dichroic mirror for the pump radiation and b) the high mechanical stability obtained by a leaf spring flexure mount of the movable Michelson mirror and by restricted alignment devices.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    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
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