Title :
Design of Balanced Mixers for ALMA Band-10
Author :
Shitov, Sergey V. ; Koryukin, Oleg V. ; Uzawa, Yoshinori ; Noguchi, Takashi ; Uvarov, Andrey V. ; Bukovski, Maksim A. ; Cohn, Ilya A.
Author_Institution :
Japan Nat. Astron. Obs., Tokyo
fDate :
6/1/2007 12:00:00 AM
Abstract :
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. TRX considerably below 200 K (DSB) is simulated using high-quality hybrid SIS junction for NbTiN/Nb - AlOx - Nb/Al for Jc = 12 kA/cm2.
Keywords :
lens antennas; microstrip antennas; microstrip lines; superconductor-insulator-superconductor mixers; 3 dB loss; ALMA Band-10; Tucker´s theory; balanced mixers; compact single-chamber balanced waveguide mixer; geometry transformation method; intervening optics; lens-antenna cartridge; lens-antenna mixer; signal loss; superconducting microstrips; twin-SIS structure; Frequency; Geometrical optics; Lenses; Microstrip; Niobium; Optical waveguide theory; Optical waveguides; Solid modeling; Superconducting devices; Telescopes; ALMA project; SIS mixer; balanced mixer; lens antenna; superconducting microstrip line;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2007.897860
