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  • 1
    Electronic Resource
    Electronic Resource
    An SIS waveguide heterodyne receiver for 600 HGz-635 GHz (1994)
    Springer
    International journal of infrared and millimeter waves 15 (1994), S. 349-368 
    Details
    ISSN: 1572-9559
    Keywords: superconductors ; SIS junctions ; SIS mixers ; SIS receivers ; submillimeter waves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A waveguide SIS heterodyne receiver using a Nb/AlOX/Nb junction has been built for astronomical observations of molecular transitions in the frequency range 600 GHz - 635 GHz, and has been successfully used at the Caltech Submillimeter Observatory (CSO). We report double sideband (DSB) receiver noise temperatures as low as 245 K at 600 GHz -610 GHz, and near 300 K over the rest of the bandwidth. These results confirm that SIS quasiparticle mixers work well at submillimeter-wave frequencies corresponding to photon energies of at least 90% of the superconductor energy gap. In addition, we have systematically investigated the effect on the receiver performance of the overlap between first-order and second-order photon steps of opposite sign at these frequencies. The receiver noise increases by as much as 40% in the region of overlap. We infer potential limitations for operating submillimeter-wave Nb/AlOx/Nb mixers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02096246
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    Paper (German National Licenses)
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  • 2
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    An SIS waveguide heterodyne receiver for 600 HGz-635 GHz (1994)
    Springer
    Details
    Publication Date: 1994-02-01
    Print ISSN: 1866-6892
    Electronic ISSN: 1866-6906
    Topics: Physics
    Published by Springer
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    PAPER CURRENT
  • 3
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    A planar quasi-optical SIS receiver (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A planar, quasi-optical SIS receiver operating at 230 GHz is described. The receiver consists of a 2 x 5 array of half wave dipole antennas with ten niobium-aluminum oxide-niobium SIS junctions on a quartz dielectric-filled parabola. The 1.4 GHz intermediate frequency is coupled from the mixer via coplanar strip transmission lines and 4:1 balun transformers. The receiver is operated at 4.2 K in a liquid helium immersion cryostat. We report accurate measurements of the performance of single receiver elements. A mixer noise temperature of 89 K DSB, receiver noise temperature of 156 K DSB, and conversion loss of 3 dB into a matched load have been obtained.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: IEEE Transactions on Microwave Theory and Techniques (ISSN 0018-9480); 41; 4; p. 609-615.
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Sub micron area Nb/AlO(x)/Nb tunnel junctions for submillimeter mixer applications (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: In this paper, we report on a fabrication process developed for submicron area tunnel junctions. We have fabricated Nb/AlO(x)/Nb tunnel junctions with areas down to 0.1 sq micron using these techniques. The devices have shown excellent performance in receiver systems up to 500 GHz and are currently in use in radio astronomy observatories at 115, 230, and 500 GHz.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Michigan Univ., The Third International Symposium on Space Terahertz Technology: Symposium Proceedings; p 408-418
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Onset of dispersion in Nb microstrip transmission lines at submillimeter wave frequencies (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: We have measured the dispersion in phase velocity of a Nb-SiO(x)-Nb microstrip transmission line resonator over a frequency range from 50 GHz to 800 GHz. A submicron Nb/Al-AlO(x)/Nb Josephson junction was used as a voltage-controlled oscillator to excite the high order modes in the resonator. The same junction is used as a direct detector resulting in a series of step-like structures in the DC current-voltage characteristic at the position of each mode frequency. The transmission line is dispersionless up to about 500 GHz where the phase velocity begins to decrease. This is well below the gap frequency f(sub g) approx. equals 700 GHz. Results agree qualitatively with the expected theoretical behavior near f(sub g). This onset of dispersion and loss in Nb transmission lines will have a significant impact on the design of submillimeter wave RF circuits.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Michigan Univ., The Third International Symposium on Space Terahertz Technology: Symposium Proceedings; p 362-381
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  • 6
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    Fabrication and characterization of high current-density, submicron, NbN/MgO/NbN tunnel junctions (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: At near-millimeter wavelengths, heterodyne receivers based on SIS tunnel junctions are the most sensitive available. However, in order to scale these results to submillimeter wavelengths, certain device properties should be scaled. The tunnel-junction's current density should be increased to reduce the RC product. The device's area should be reduced to efficiently couple power from the antenna to the mixer. Finally, the superconductor used should have a large energy gap to minimize RF losses. Most SIS mixers use Nb or Pb-alloy tunnel junctions; the gap frequency for these materials is approximately 725 GHz. Above the gap frequency, these materials exhibit losses similar to those in a normal metal. The gap frequency in NbN films is as-large-as 1440 GHz. Therefore, we have developed a process to fabricate small area (down to 0.13 sq microns), high current density, NbN/MgO/NbN tunnel junctions.
    Keywords: SOLID-STATE PHYSICS
    Type: Michigan Univ., The Third International Symposium on Space Terahertz Technology: Symposium Proceedings; p 420-438
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    NASA TECHNICAL REPORTS
  • 7
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    A planar quasi-optical SIS receiver for array applications (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A planar, quasi-optical SIS receiver operating at 230 GHz is described. The receiver consists of a 2 x 5 array of half wave dipole antennas with ten niobium-aluminum oxide-niobium SIS junctions on a quartz dielectric-filled parabola. The 1.4 GHz intermediate frequency is coupled from the mixer via coplanar strip transmission lines and 4:1 balun transformers. The receiver is operated at 4.2 K in a liquid helium immersion cryostat. We report accurate measurements of the performance of single receiver elements. A mixer noise temperature of 89 K DSB, receiver noise temperature of 156 K DSB, and conversion loss of 3 dB into a matched load have been obtained.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Michigan Univ., The Third International Symposium on Space Terahertz Technology: Symposium Proceedings; p 235-242
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  • 8
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    A Prototype Quasi-Optical SIS Array Receiver (1993)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Description: We report measurements on a prototype SIS array receiver consisting of a ten-element dipole antenna array with half square micron niobium SIS junctions.
    Keywords: Communications and Radar
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    A fixed tuned broadband matching structure for submillimeter SIS receivers (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: We have designed, fabricated, and tested a quasi-optical spiral antenna mixer with a Nb/AlO(x)/Nb tunnel junction. This design incorporates a hybrid antenna fed by a planar logarithmic spiral antenna to couple to the radiation field, as previously done with Pb based devices, as well as a newly designed matching circuit. This matching circuit is a relatively complex structure requiring several layers of photolithographic processing on top of the actual tunneling device. Computer modeling of the device predicted the measured bandwidth to within 8 percent, making scale model measurements unnecessary. We have obtained a good match from 210 GHz to 460 GHz between the antenna and a relatively large area (1.25 by 1.25 sq microns) tunnel junction with omega R(sub N) C approx. = 2 - 4.4. This compares to simple inductive stubs that attain only a few percent of total bandwidth in the submillimeter band or inductively tuned SIS arrays with an upper limit of operating frequencies well below the submillimeter band. Noise temperatures were measured at 345 GHz, 426 GHz, and 492 GHz yielding double sideband noise temperatures at 200 K, 220 K, and 500 K, respectively.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Michigan Univ., The Third International Symposium on Space Terahertz Technology: Symposium Proceedings; p 243
    Format: text
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  • 10
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    Edge geometry superconducting tunnel junctions utilizing an NbN/MgO/NbN thin film structure (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An edge defined geometry is used to produce very small area tunnel junctions in a structure with niobium nitride superconducting electrodes and a magnesium oxide tunnel barrier. The incorporation of an MgO tunnel barrier with two NbN electrodes results in improved current-voltage characteristics, and may lead to better junction noise characteristics. The NbN electrodes are preferably sputter-deposited, with the first NbN electrode deposited on an insulating substrate maintained at about 250 C to 500 C for improved quality of the electrode.
    Keywords: SOLID-STATE PHYSICS
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