Tunable microwave characteristics of a superconducting planar transmission line by using a nonlinear dielectric thin film

Abstract

A field solution for a planar type-II superconducting transmission line made of two high-temperature superconducting films and a nonlinear dielectric thin film is derived. The combined effects of the nonlinear dielectric permittivity as well as of vortices inside the superconductors on the attenuation constant and phase velocity are numerically investigated. Variation in temperature-dependent phase velocity due to the dielectric nonlinearity is lowered pronouncedly in the presence of vortices. In addition, variation in phase velocity versus dc electric field is also reduced in the case of more vortices. The role played by the nonlinear dielectric as well as the vortices in such a tunable microwave component are thus demonstrated.

Attenuation in a Cylindrical Left Handed Material (LHM) Wave-Guide Structure

“…The propagation of waves in superconductor media have drowned much attention and consideration [18]. The use of superconducting thin films in transmission line is advantageous for signal processing because films are low loss and they are with wide bandwidth [19]. The loss can be described in terms of the surface resistance of the superconductor and it is also related to the attenuation constant of the superconductor.…”

Microwave Properties of a High-Temperature Superconductor and Ferromagnetic Bilayer Structure

“…For YBCO, the relevant dielectric substrate includes lanthanum aluminate, LaAlO 3 , magnesium oxide, MgO, and strontium titanate, SrTiO 3 (STO), as well. In the YBCO/STO layered structure, the temperature-dependent effective surface resistance shows an oscillating behavior because the permittivity of STO is nonlinear, i.e., it is strongly dependent on the temperature and the external applied static electric field [12,13]. Using semiconductor Si as a substrate, the study of surface impedance of YBCO/Si has been reported recently [14].…”