Vortex dynamics effects on microwave propagation in high temperature superconducting coplanar waveguides

摘要

An analysis of the microwave signal propagation through a High Temperature Superconducting (HTS) transmission line should take into account the vortex dynamics effects of the HTS material used for the study. Taking Coplanar Waveguide (CPW) as a model transmission line, we simulated the transmission characteristics using a field computation method based on Galerkin's procedure. The vortex effects were incorporated into the study using the surface impedance derived from the modified two-fluid model proposed by Coffey and Clem which takes into account the field and thermal effects in a self consistent manner. The increase of temperature and magnetic field significantly affected the attenuation due to the enhanced vortex motion. The observed dip in the value of attenuation of the transmission line at low field values in high temperature range is explained using the vortex effects. It is found that the dispersion is considerably low for the proposed geometrical structures. Simulations were performed for varying strip-to-slot ratios. The impact of vortex motion on the signal propagation is made out for a wide range of temperature, magnetic field, and line geometry.