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Author Myasnikova, S. E.; Parshin, V.V.; van't Klooster, K.; Valsecchi, G.
Title Reflectivity of antenna and mirrors reflectors at 110 and 200 GHz Type Conference Article
Year 2003 Publication Proc. 4th international conference on antenna theory and techniques Abbreviated Journal
Volume 2 Issue Pages 624- 627
Keywords (up) mirror, reflection index, emissivity, reflectivity, mirror, Fabry-Perot interferometer, subterahertz, subTHz
Abstract Reflectivity (reflection loss) investigations of nickel samples with different types of surface finish, with and without rhodium coating, have been carried out in the 110-200 GHz frequency range on an installation developed in the Applied Physics Institute of Russia. The reflectivity measurements of high quality silver coated and gold coated mirrors are also presented. The reflectivity (reflection loss) investigations of some carbon fibre samples with and without aluminium coating have been made. Results are interesting, in view of the anisotropy of the carbon fibre material.
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Call Number Serial 582
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Author van't Klooster, C. G. M.; Parshin, V. V.; Myasnikova, S. E.
Title Reflectivity of antenna reflectors: measurements at frequencies between 110 and 200 GHz Type Conference Article
Year 2003 Publication Proc. Antennas and propagation society international symposium Abbreviated Journal
Volume 3 Issue Pages 528-531
Keywords (up) mirror, reflection index, emissivity, reflectivity, mirror, Fabry-Perot interferometer, subterahertz, subTHz
Abstract It is imperative to test the mechanical, electrical and thermal-optical properties of MM and sub-MM reflector antennas. Electrical, thermal and optical properties are very important and high-accurate measurements lead, obviously, to more accurate results in applications. This paper deals with measurement of electrical reflectivity in the range 110-200 GHz. Reflectivity has been measured for a number of samples, which represent materials used in reflector antennas. Both metal samples and carbon-fibre samples were tested in a dedicated facility available for this purpose at the Applied Physics Institute in Nizhny Novgorod (IAP). The test facility is shortly discussed, with techniques for data extraction. Calibration is done with high quality silver coated mirrors and aluminium control samples. Accurate results have been derived with indicative interesting results.
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Notes Approved no
Call Number Serial 583
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Author Tinkham, M.; Free, J. U.; Lau, C. N.; Markovic, N.
Title Hysteretic I–V curves of superconducting nanowires Type Journal Article
Year 2003 Publication Phys. Rev. B Abbreviated Journal
Volume 68 Issue Pages 134515(1 to 7)
Keywords (up) MoGe nanowires, self-heating effect
Abstract Experimental I–V curves of superconducting MoGe nanowires show hysteresis for the thicker wires and none for the thinner wires. A rather quantitative account of these data for representative wires is obtained by numerically solving the one-dimensional heat flow equation to find a self-consistent distribution of temperature and local resistivity along the wire, using the measured linear resistance R(T) as input. This suggests that the retrapping current in the hysteretic I–V curves is primarily determined by heating effects, and not by the dynamics of phase motion in a tilted washboard potential as often assumed. Heating effects and thermal fluctuations from the low-resistance state to a high-resistance, quasinormal regime appear to set independent upper bounds for the switching current.
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Notes Approved no
Call Number Serial 918
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Author Meledin, D.; Tong, C. Y.-E.; Blundell, R.; Kaurova, N.; Smirnov, K.; Voronov, B.; Gol'tsman, G.
Title Study of the IF bandwidth of NbN HEB mixers based on crystalline quartz substrate with an MgO buffer layer Type Journal Article
Year 2003 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 13 Issue 2 Pages 164-167
Keywords (up) NbN HEB mixer
Abstract In this paper, we present the results of IF bandwidth measurements on 3-4 nm thick NbN hot electron bolometer waveguide mixers, which have been fabricated on a 200-nm thick MgO buffer layer deposited on a crystalline quartz substrate. The 3-dB IF bandwidth, measured at an LO frequency of 0.81 THz, is 3.7 GHz at the optimal bias point for low noise receiver operation. We have also made measurements of the IF dynamic impedance, which allow us to evaluate the intrinsic electron temperature relaxation time and self-heating parameters at different bias conditions.
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Notes Approved no
Call Number Serial 341
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Author Huebers, H.-W.; Semenov, A.; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Smirnov, K.; Gol’tsman, G. N.; Voronov, B. M.
Title Superconducting hot electron bolometer as mixer for far-infrared heterodyne receivers Type Conference Article
Year 2003 Publication Proc. SPIE Abbreviated Journal Proc. SPIE
Volume 4855 Issue Pages 395-401
Keywords (up) NbN HEB mixers
Abstract Heterodyne receivers for applications in astronomy need quantum limited sensitivity. In instruments which are currently under development for SOFIA or Herschel superconducting hot electron bolometers (HEB) will be used to achieve this goal at frequencies above 1.4 THz. We present results of the development of a phonon-cooled NbN HEB mixer for GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be flown aboard SOFIA. The mixer is a small superconducting bridge incorporated in a planar feed antenna and a hyperhemispherical lens. Mixers with logarithmic-spiral and double-slot feed antennas have been investigated with respect to their noise temperature, conversion loss, linearity and beam pattern. At 2.5 THz a double sideband noise temperature of 2200 K was achieved. The conversion loss was 17 dB. The response of the mixer was linear up to 400 K load temperature. The performance was verified by measuring an emission line of methanol at 2.5 THz. The measured linewidth is in good agreement with the linewidth deduced from pressure broadening measurements at millimeter wavelength. The results demonstrate that the NbN HEB is very well suited as a mixer for far-infrared heterodyne receivers.
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Publisher SPIE Place of Publication Tucson, USA Editor Phillips, T. G.; Zmuidzinas, J.
Language Summary Language Original Title
Series Editor Series Title Presented at the Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Abbreviated Series Title
Series Volume 4855 Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference Millimeter and Submillimeter Detectors for Astronomy
Notes Approved no
Call Number Serial 335
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