Superconducting Receiver Front-End and Its Application In Meteorological Radar

The discovery of superconductivity is one of the greatest achievements in fundamental sciences of 20th century. Nearly one hundred year ago, the Dutch physicist H. Kamerlingh Onnes found that the resistance of pure mercury abruptly dropped to zero at liquid helium temperature 4.2K (Kammerlingh Onnes, 1911). Since then scientists tried very hard to find more superconducting materials and to understand this microscopic quantum phenomenon, which has greatly pushed forward the development of modern physics. Enormous progress has been made since 1986, when the so called high temperature superconductors (HTS) were discovered (Bednorz & Mueller, 1986). Superconductivity becomes not only a branch of fundamental sciences but also a practical technology, ready for applications. It is commonly recognized that the first application of HTS thin films is in high performance microwave passive devices, especially filters. As a successful example the application of HTS filter in meteorological radar will be introduced. In this chapter firstly the fundamental concepts of superconductivity will be summarized and then the basic principles of superconducting technology at microwave frequency will be briefly outlined. Then the design and construction of superconducting filters and microwave receiver front-end subsystems will be discussed. Finally results of field trial of the world first superconducting meteorological radar will be introduced and conclusions will then be drawn.