Thin film high temperature superconducting radio frequency resonators and filters, and their applications

This thesis examines the design, fabrication, and the application of thin film high temperature superconducting (HTS) radio frequency (RF) resonators and filters. Due to the low surface resistance of HTS materials, thin film HTS resonators and filters have shown relative advantages to conventional counterparts, such as lower resistive losses, smaller sizes, and higher selectivity.; The application of HTS resonators with high quality factor (Q-value) as receiver coils to magnetic resonance imaging (MRI) can increase the MRI system signal-to-noise (SNR) ratio a few times higher than conventional copper coils, which in return can improve the image quality significantly with the same imaging parameters. Two different designs, namely interdigital and spiral, have shown great success for both high and low field MRI (from 4.2 T to 0.2 T) applications. The issues related with high Q HTS resonator design and fabrication will be addressed in detail, such as how to minimize the coil conductive loss, dielectric loss and radiation loss.; Based on the structure of spiral coils, HTS RF filters have been designed with transformer coupled resonators configuration. This design eliminated the affects by the parasitics and metalization that limited the performance of HTS RF filters with interdigital capacitors and meander-line inductors. The transformer-coupled resonators have shown low insertion losses, and sharp skirts, demonstrating their potential application as pre-select filter in MRI system and communication systems.