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.

Indexing terms:

• HTSC filters
• Microwave superconductor
• Thin film HTSC filters

Additional information

Notes on contributors

B K Sarkar

B K Sarkar passed BTech in 1967, MTech in 1969 and PhD in 1981 from IIT Medras, NT Kharagpur and IIT Bombay respectively, initially he joined the Tata Institute of Fundamental Research, Mumbai where he worked as Scientific Officer from 1969 to 1985,. Subsequently, he was transferred to Society for Applied Microwave Electronics Engineering and Research (SAMEER) under the Department of Electronics, Government of India, at present, he is holding the post of Associate Director. He has worked for the last 30 years on Semiconductor devices and its applications, antenna and special purpose radar systems. He has published as many as 95 papers in the journals and proceedings of symposia in India and abroad. He is a senior member of Society of EMC Engineers, India.

R Pinto

R Pinto, has been actively engaged in research at the Tata Institute of Fundamental Research since 1964. He obtained PhD Degree in Physics in 1972 from TIFR/University of Bombay, India. He has served as a member of national committees for the development of advanced devices such as charge coupled imagers and magneto-optic devices, and was awarded the 1997 MRS (India) Medal. Currently, Professor Pinto heads the high T_c thin film microwave device program in collaboration with Society for Applied Microwave Electronic Engineering and Research (SAMEER), Mumbai, India and Space Applications Centre (SAC), Ahmedabad, India.