Microwave components and devices based on high temperature superconductors

High temperature superconductors (HTS), just after discovery, were investigated and oriented for practical applications at microwave frequencies. The following areas of HTS study at microwaves are specified: 1. Low loss transmission lines and high quality resonators and filters; 2. Signal limiters, switches and digital phase shifters based on the transition from superconducting to normal state of the HTS material (S-N transition); 3. Bolometers and resistive type mixers for frequencies up to a few THz; 4. Applications of the Josephson effect to the generation and detection of THz frequency signals and to frequency measurement and spectroscopy. All these applications are realized at the operational temperature of 60-80 K. YBa₂Cu₃O₇ epitaxial films on single crystal substrate are commonly used. The temperature of the superconductive phase transition of the films is about 90 K. The films can be fabricated on the industrial level