Microwave Studies Of High Temp Superconductors

Studies Of High Temperature Superconductors Volume 17 -- Microwave Studies Of High Temperature Perconductors

Six chapters report recent research on high-temperature superconductors from the perspectives of radio-frequency investigations, microwave surface impedance and device applications, mixed state and superconducting fluctuations in single crystals, circuits and systems, microwave and radio- frequency

Detailed coverage of all aspects of microwave superconductivity: fundamentals, fabrication, measurement, components, circuits, cryogenic packaging and market potential. Both a graduate-level textbook and a reference for microwave engineers. Applications (with either active or passive circuit elements) include those at both liquid-helium and liquid-nitrogen temperatures. Topics covered include wireless communications, space-based cryoelectronics, SQUIDs and SQUID amplifiers, NMR and MRI coils, accelerator cavities, and Josephson flux-flow devices.

This book describes the application of new high temperature superconducting materials to microwave devices and systems. It deals with the fundamentals of the interaction between microwaves and superconductors, and includes a basic description of how microwave devices can be constructed using these materials. Since the discovery of high temperature superconductors in 1986 there has been an enormous effort worldwide to develop and characterize these materials. Work on applications has proceeded more slowly however. Nevertheless, commercial applications are now beginning to arise, including use in passive microwave devices. The author carefully describes the advantages of using high temperature superconductors in these devices, enabling scientists and engineers to form a complete understanding of the subject. The rest of the book is devoted to examples of superconducting microwave filters, antennas and systems. The examples chosen relate not only to what can be achieved at present, but indicate the trends for future research and what may be expected for superconducting devices in the future. The book will appeal to researchers in electrical and electronic engineering.

These lectures are concerned with the application of high temperature superconductors to both passive and active high-frequency devices.The central issue addressed is the electrodynamics of granular superconductors, particularly where grain boundaries (either natural or synthetic) act as Josephson weak-links. Grain boundaries are responsible for residual dissipation and for unwanted dependence of the electromagnetic properties on ambient magnetic fields and on elevated power level. Properly controlled, similar weak-links are the key to high sensitivity dc and rf SQUIDS at readily accessible temperatures, and to modulators, mixers and detectors. Such structures may conveniently lead to superconductive electronic devices as well as coherent sources of radiation in the very far infrared.

The book develops a comprehensive understanding of the surface impedance of the oxide high-temperature superconductors in comparison with the conventional superconductor Nb3Sn. Linear and nonlinear microwave responses are treated separately, both in terms of models, theories or numerical approaches and in terms of experimental results. The theoretical treatment connects fundamental aspects of superconductivity to the specific high-frequency properties. The experimental data review the state of the art, as reported by many international groups. The book describes further the main features of appropriate preparation, handling, mounting, and refrigeration techniques, and finally discusses possible applications in passive and active microwave devices.

High-temperature superconducting (HTS) materials are becoming more and more attractive in the context of designing RF/microwave filters because of their lower losses and excellent performance. This book focuses on the superconducting microwave filter and its application in modern communication. It first presents the basic principles, HTS materials and processing and then introduces several types of multi-band HTS bandpass filter (BPF), discussing their properties and analyzing equivalent circuit models and their performances. This book is a valuable resource for students and researchers who are interested in wireless communication and RF/microwave design.