High Temperature Superconducting thin film Microwave Filters

Abstract

We have successfully developed low loss thin films of high temperature superconductors (HTSC) on MgO as well as LaAIO3 substrates. This effort aims at the development of application oriented innovations, such as HTSC based passive microwave devices. As an initial attempt in developing microwave devices, we have designed, fabricated and tested HTSC microstrip resonators at X-band using YBCO thin films on LaAIO3 substrates. The film was grown using Pulsed Laser Ablation Technique. These resonators were tested and found to have quality factors up to 4500 in microstrip configuration and upto 10,000 in inverted microstrip configuration. These test results are presented in this paper. Superconducting Microwave Filters with high Q and very small size have been designed in various microstripline configurations. Design analysis and sensitivity analysis are carried out and simulated results are presented. The design is on LaAIO3 substrate of size 11 mm x 6mm x 0.5 mm, for C-band, five section filter. The hairpin configuration used for the filter reduces the size of the filter considerably than using a conventional parallelcoupled configuration, but with increased pass band loss. The structure is analysed by IE3D electromagnetic simulator and simulated results are presented.