Design of Balanced Mixers for ALMA Band-10

Two variants of balanced mixer employing twin-SIS structure are under development for 787-950 GHz frequency range. Easy-to-use Geometry Transformation method for modeling of superconducting microstrips is developed, compared to referenced methods and used for design of the mixers. Lens-antenna mixer...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2007-06, Vol.17 (2), p.347-350
Main Authors: Shitov, S.V., Koryukin, O.V., Uzawa, Y., Noguchi, T., Uvarov, A.V., Bukovski, M.A., Cohn, I.A.
Format: Article
Language:English
Subjects:
ALMA project
Aluminum
balanced mixer
Balancing
Cartridges
Frequency
Geometrical optics
lens antenna
Lenses
Mathematical models
Microstrip
Mixers
Niobium
Noise levels
Optical waveguide theory
Optical waveguides
SIS mixer
Solid modeling
Superconducting devices
superconducting microstrip line
Superconductivity
Telescopes
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Summary:Two variants of balanced mixer employing twin-SIS structure are under development for 787-950 GHz frequency range. Easy-to-use Geometry Transformation method for modeling of superconducting microstrips is developed, compared to referenced methods and used for design of the mixers. Lens-antenna mixer is based on cross-slot antenna; it does not need any intervening optics between its lens and sub-reflector of ALMA telescope; simple yet efficient composition of lens-antenna cartridge is suggested. Compact single-chamber balanced waveguide mixer employs two SIS chips and capacitive probe for LO injection; coupling above -3 dB and signal loss below -20 dB are expected. Need in shifting of resonance frequency of twin-SIS mixer towards top of the frequency band is predicted using Tucker's theory in large-signal approximation. T RX considerably below 200 K (DSB) is simulated using high-quality hybrid SIS junction for NbTiN/Nb - AlO x - Nb/Al for J c = 12 kA/cm 2 .
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2007.897860