5-GHz high temperature superconducting filter using coplanar waveguide quarter wavelength resonator

This paper presents a 5-GHz high temperature superconducting (TITS) filter that employs coplanar waveguide quarter wavelength resonators. The fabricated four-pole Chebyshev HTS bandpass filter applies photolithography and ion milling to form a precise filter circuit pattern on Yttrium Barium Copper Oxide film. The filter has a center frequency of 5.02 GHz, a 4.0% (200 MHz) equal ripple bandwidth, 0.13 dB ripple, and 0.22 dB average insertion loss, all measured at 60 K. This insertion loss is quite low compared to that of the HTS filters employing CPW resonators reported so far.