ELECTROMAGNETIC DESIGN OF HIGH-TEMPERATURE SUPERCONDUCTING MICROWAVE FILTERS

We present novel approaches to electromagnetic design of high-temperature superconducting (HTS) quarter-wave parallel coupled-line microstrip filters. The desired narrow bandwidths (less than 2%) coupled with the large dielectric constant of substrate materials used in the HTS technology (epsilon(r) approximate to 24) make the design problems difficult to treat accurately for many traditional microwave circuit design software packages with analytical/empirical models, We have successfully performed an HTS filter design with accurate electromagnetic field simulations. We discuss problems related to electromagnetic design of such filters. We describe a look-up table method and a powerful space mapping optimization technique, which dramatically reduce the CPU time needed in the design process, Finally, we address the issue of improved modeling of the HTS filter using analytical/empirical models. (C) 1995 John Wiley and Sons, Inc.