HIGH-TEMPERATURE SUPERCONDUCTING MICROWAVE DEVICES - FUNDAMENTAL ISSUES IN MATERIALS, PHYSICS, AND ENGINEERING

High-T(c) superconductivity has generated a great deal of interest bec ause of the challenges it presents in the fields of material science, condensed matter physics, and electrical engineering, and because of t he potential applications which may result from these research efforts . Thin-film passive microwave components may become the first high-tem perature superconducting (HTS) devices available for widespread use an d commercialization. In this article, we review aspects of material sc ience, physics, and engineering which directly impact high-T(c) superc onducting microwave devices and discuss issues which determine the per formance of these devices. Methods of growing HTS thin films on large- area substrates, techniques for fabricating single-level HTS passive m icrowave components, and the relevant properties of high-T(c) supercon ducting films are discussed, with a focus on thin films of the HTS mat erial YBa2Cu3O7-delta. Several known mechanisms for microwave loss in both the superconductor and the dielectric substrate are presented. An overview of the general classes of superconducting passive microwave devices is given, and representative microwave devices which have been recently demonstrated are described in detail. Examples of a select f ew HTS active microwave components are also presented. Potential micro wave applications are illustrated with comparisons to current technolo gy.