The benefits and potential applications of superconducting thin films, such as yttrium barium copper oxide, thallium barium calcium copper oxide, lanthanum barium copper oxide, and lanthanum strontium copper, will be identified, along with their transition temperature limits. The benefits of these films in the design and development of radiofrequency (RF) filters, traveling wave-tube amplifiers
(TWTAs), electromagnetic devices, low-frequency antennas, microwave solid state devices, yttrium iron garnet (YIG)-tuned filters with sharp cutoff characteristics in the stop-band regions, and underwater detecting sensors will be highlighted . Properties of potential superconducting substrates will be summarized. The performance parameters of yttrium aluminum garnet (YAG), YIG, and other superconducting substrates will be summarized. Performance improvement in RF and high-frequency microwave components or devices will be summarized as a function of superconducting temperatures. YAG-tuned transistor design will be discussed, with an emphasis on tuning range and efficiency at higher RF frequencies. Rare earth materials used in the design and development of permanent magnets for various commercial and industrial applications will be identified, with particular emphasis on weight and size reductions, performance improvement, and enhanced reliability while the rare earth magnets are operating under harsh thermal and mechanical environments .