Superconducting microstrip line models at millimeter and sub-millimeter waves and their comparison

• Performance of superconductor — insulator - superconductor (SIS) tunnel junction mixers andtheir instantaneous input RF bandwidth are mostly depending on the integrated tunin g circuit used to resonate out SIS junction capacitance; Nb-based SIS mixers operate in the frequency range of about 80 - 1000 GHz and typically use microstrip-based integrated tuning circuitries.One of the major challenges in designing the tuning circuitry for SIS mixers is accuracy of models for superconducting microstrip line (SML). Modeling gives the only tool to solve the problem of designing SML-based circuits because for such high frequencies no direct measurements of a superconducting transmission line can be made with required high accuracy.However, creating an accurate model for such a superconducting transmission line is a challengeby itself. In the SML, produced usually by thin-film technology, the magnetic field penetrationdepth is comparable with the thicknesses of the dielectric and superconductors comprising theline. As a result the electromagnetic wave is propagated not only in the dielectric media but alsoinside the superconducting strip and ground electrodes constituting the SML. This createsdramatic changes in the transmission line behavior that should be carefully accounted byincluding the superconducting material properties into the modeling. Nb superconductor, as themost commonly exploited material, was used in this study for modeling of the superconductingmicrostrip though the same approach would work for any different BCS superconductingmaterial. The purpose of this paper is to introduce a new model for SML and compare it withpreviously suggested models and results of SML numerical simulation.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Rymd- och flygteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Aerospace Engineering (hsv//eng)

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Annan elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Other Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

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