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Author Gol'tsman, G.; Maslennikov, S.; Finkel, M.; Antipov, S.; Kaurova, N.; Grishina, E.; Polyakov, S.; Vachtomin, Y.; Svechnikov, S.; Smirnov, K.; Voronov, B.
Title Nanostructured ultrathin NbN film as a terahertz hot-electron bolometer mixer Type Conference Article
Year 2006 Publication Proc. MRS Abbreviated Journal Proc. MRS
Volume 935 Issue Pages (up) 210 (1 to 6)
Keywords NbN HEB mixers
Abstract Planar spiral antenna coupled and directly lens coupled NbN HEB mixer structures are studied. An additional MgO buffer layer between the superconducting film and Si substrate is introduced. The buffer layer enables us to increase the gain bandwidth of a HEB mixer due to better acoustic transparency. The gain bandwidth is widened as NbN film thickness decreases and amounts to 5.2 GHz. The noise temperature of antenna coupled mixer is 1300 and 3100 K at 2.5 and 3.8 THz respectively. The structure and composition of NbN films is investigated by X-ray diffraction spectroscopy methods. Noise performance degradation at LO frequencies more than 3 THz is due to the use of a planar antenna and signal loss in contacts between the antenna and the sensitive NbN bridge. The mixer is reconfigured for operation at higher frequencies in a manner that receiver’s noise temperature is only 2300 K (3 times of quantum limit) at LO frequency of 30 THz.
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ISSN 0272-9172 ISBN Medium
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Notes Approved no
Call Number Serial 1440
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Author Meledin D.; Pantaleev M.; Pavolotsky A.; Risacher C.; Robles V.A.P.; Belitsky V.; Drakinskiy V.; Cherednichenko S.
Title Design of a balanced waveguide HEB mixer for APEX 1.32 THz receiver Type Conference Article
Year 2004 Publication Proc. 15th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages (up) 211-217
Keywords
Abstract The prototype of a waveguide balanced Hot Electron Bolometer (HEB) Terahertz mixer is designed as a part of development for the APEX Project of Band T2 receiver for 1250-1390 GHz. The proposed mixer employs balanced scheme with two identical HEB devices. These individual mixers would be placed on two separate crystalline quartz substrates with dimensions of 1000μm x67μm x17 μm each with integrated RF choke filters, DC-bias and IF circuitry. A 3 dB quadrature waveguide directional coupler is needed to provide local oscillator (LO) injection and RF signal distribution between the two HEB mixers. We have designed the coupler to achieve the required frequency band, low insertion loss and symmetrical division of the RF and LO power within the band of interest. Initial design of HEB mixer layout is developed based on a previous development for a 345 GHz sideband separation mixer. We present also results of development of microfabrication technology of the waveguide hybrid employing micromachining approach combined with electroplating technique.
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Call Number RPLAB @ atomics90 @ Serial 972
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Author Godunova, E. K.; Levin, V. I.
Title Some general features of heat conduction Type Journal Article
Year 1966 Publication USSR Computational Mathematics and Mathematical Physics Abbreviated Journal USSR Computational Mathematics and Mathematical Physics
Volume 6 Issue 6 Pages (up) 212-220
Keywords mathematics, temperature distribution, rod
Abstract LET the initial temperature distribution in an infinite insulated rod without a heat source be given by a continuously differentiable function y = f(x), having a single maximum at x = 0 and two points of inflexion. The equation f′ = 0 then has a unique solution x = 0, where f′(x) > 0 for x < 0 and f′(x) < 0 for x > 0, We shall describe this as a one-hymped distribution. We shall assume that f/(x) also satisfies: (1) f(x) > 0 for − ∞ < x < ∞; (2) f(x) and x(fx) are integrable throughout the axis. Then the distribution remains one-humped for all t > 0.
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ISSN 0041-5553 ISBN Medium
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Notes Некоторые качественные вопросы теплопроводности; Одногорбое распределение останется одногорбым Approved no
Call Number Serial 1701
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Author 0kunev, 0.; Dzardanov, A.; Ekstrom, H.; Jacobsson, S.; Kollberg, E.; Gol'tsman, G.; Gershenzon, E.
Title NbN hot electron waveguide mixer for 100 GHz operation Type Conference Article
Year 1994 Publication Proc. 5th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 5th Int. Symp. Space Terahertz Technol.
Volume Issue Pages (up) 214-224
Keywords waveguide NbN HEB mixers
Abstract NbN is a promising superconducting material used to develope hot- electron superconducting mixers with an IF bandwidth over 1 GHz. In the 100 GHz frequency range, the following parameters were obtained for NbN films 50 A thick: the noise temperature of the receiver (DSB) 1000 K; the conversion losses 10 d13, the IF bandwidth 1 GHz; the local oscillator power 1 /LW. An increase of NbN film thickness up to 80-100 A and increase of working temperature up to 7-8 K, and a better mixer matching may allow to broader the IF band up to 3 Gllz, to reduce the conversion losses down to 3-5 dB and the noise tempera- ture down to 200-300 K.
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Notes Approved no
Call Number Serial 1644
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Author Wyss, R. A.; Karasik, B. S.; McGrath, W. R.; Bamble, B.; LeDuc, H.
Title Noise and bandwidth measurements of diffusion–cooled Nb hot–electron bolometer mixers at frequencies above the superconductive energy gap Type Conference Article
Year 1999 Publication Proc. 10th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages (up) 215-229
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Publisher Place of Publication Charlottesville, Virginia Editor
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Notes Approved no
Call Number RPLAB @ s @ qoheb_Tn_1250_at_1p1 Serial 293
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