Abstract
The Superconductor-Insulator-Superconductor (SIS) tunnel junction is an extremely sensitive heterodyne detector at millimeter and submillimeter wavelengths. The large inherent capacitance associated with this device results in a substantial impedance mismatch with typical antennas and, therefore, requires a tuning circuit for optimum results. At frequencies where waveguide dimensions are realizable, impedance matching can be accomplished by embedding the detector in a waveguide circuit with adjustable waveguide backshorts. At higher frequencies, where waveguide dimensions become prohibitively small, a planar transmission line embedding circuit provides a reasonable alternative. Typically, such planar circuits offer no post-fabrication adjustability, resulting in demanding materials and design requirements. An adjustable planar embedding circuit based on coplanar transmission lines with movable noncontacting shorting elements has been developed. The shorting elements each consist of a thin metallic plate with an optimized arrangement of rectangular holes, placed along the insulated metallic transmission line to provide a periodic variation of the line impedance. A scadel (1–5 GHz) has shown that a large reflection coefficient, |s 11|≥−0.5 dB, can be achieved with these sliding elements. A low frequency tuning circuit incorporating these shorting elements has been tested to demonstrate practical tuning ranges.
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References
J.R. Tucker and M.J. Feldman, “Quantum Detection at Millimeter Wavelengths,”Reviews of Modern Physics, vol. 57, no. 4, pp. 1055–1113, October 1985.
B.N. Ellison, P.L. Schaffer, W. Schaal, D. Vail, and R.E. Miller, “A 345 GHz SIS Receiver For Radio Astronomy,”International Journal of Infrared and Millimeter Waves, vol. 10, no. 8, pp. 937–947, 1989.
S-K. Pan, A.R. Kerr, M.J. Feldman, A.W. Kleinsasser, J.W. Stasiak, R.L. Sandstrom, and W.J. Gallagher, “An 85–116 GHz SIS Receiver Using Inductively Shunted Edge Junctions,”IEEE Transactions on Microwave Theory and Techniques, vol. 37, no. 3, pp. 580–592, March 1989.
C.A. Mears, Q. Hu, P.L. Richards, A.H. Worsham, D.E. Prober, and A.V. Raisanen, “Quantum Limited Heterodyne Detection of Millimeter Waves Using Superconducting Tantalum Tunnel Junctions,”Applied Physics Letters, vol. 57, no. 23, pp. 2487–2489, December 1990.
Q. Hu, C.A. Mears, P.L. Richards, and F.L. Lloyd, “MM Wave Quasioptical SIS Mixers,”IEEE Transactions on Magnetics, vol. 25, no. 21, pp. 1380–1383, March 1989.
W.R. McGrath, J.A. Stern, H.H.S. Javadi, S.R. Cypher, B.D. Hunt, and H.G. Le Duc, “Performance of NbN Superconducting Tunnel Junctions as SIS Mixers at 205 GHz,”IEEE Transactions on Magnetics, vol. 27, no. 2, pp. 2650–2653, March 1991.
Y.T. Lo, S.W. Lee,Antenna Handbook, Van Nostrand Reinhold Co., N. Y., p. 28–35, 1988.
S.W. Wedge, R. Compton, D. Rutledge,Puff: Computer Aided Design for Microwave Integrated Circuits, (published at Caltech, Pasadena, California), 1991.
L-S. Fan, Y-C. Tai, and R.S. Muller, “Integrated Movable Micromechanical Structures for Sensors and Actuators”,IEEE Transactions on Electron Devices, vol. 35, no. 6, pp. 724–730, June 1988.
M. Mehregany, K.J. Gabriel, and W.S.N. Trimmer, “Integrated Fabrication of Polysilicon Mechanisms,”IEEE Transactions on Electron Devices, vol. 35, no. 6, pp. 719–723, June 1988.
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Lubecke, V.M., McGrath, W.R. & Rutledge, D.B. Sliding backshorts for planar circuits. Int J Infrared Milli Waves 12, 1387–1397 (1991). https://doi.org/10.1007/BF01883872
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DOI: https://doi.org/10.1007/BF01883872