Tham khảo tài liệu 'handbook of high temperature superconductor electronics part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 10 High-Temperature Superconductor Microwave Devices Neeraj Khare National Physical Laboratory New Delhi India INTRODUCTION High-temperature superconductors have been used for microwave applications since their discovery in 1986 and there has been a continuous progress in this area. Several high-Tc superconductors based microwave devices such as resonators filters multiplexer receivers delay line antenna phase shifter and so forth with superior performances have been demonstrated 1-5 . High-Tc microwave components and subsystems are currently being commercialized by several companies. The use of high-Tc superconductors in microwave passive devices has an advantage over normal conductors such as copper and silver in terms of low insertion loss and high gain due to their lower surface resistance. Also because of lower losses in superconductors a reduction in size of the devices is an added advantage in using high-Tc superconductors. In recent years high-Tc superconductor-based filters and subsystems have been considered for application in mobile communication as well as for satellite and some specific radio astronomy applications 3 5-12 . The use of high-Tc filters in a cellular base station is being investigated for improved sensitivity. Nearly 1000 high-Tc filter subsystems have been deployed worldwide with millions of hours of cumulative operations 3 . Microwave technology based on high-Tc superconductors offer the potential of considerable miniaturization of pay-load elec Copyright 2003 by Marcel Dekker Inc. All Rights Reserved. tronic equipment in space systems leading to an overall cost reduction and accelerating the development of small satellite systems 10 . This chapter reviews the progress in the development of various high-Tc superconductor microwave passive devices such as resonators filters antenna delay lines phase shifters tunable devices and microwave subsystems. HIGH-Tc SUPERCONDUCTOR MATERIALS Several high-Tc superconductors exhibiting .
