A 5-GHz band coplanar-waveguide high temperature superconducting filter employing T-form open gap

Abstract

This paper presents a coplanar-waveguide (CPW) high-temperature superconducting (HTS) filter that has a T-form open gap as an input/output coupling structure to reduce the fluctuation in filter characteristics caused by dimension errors originating from the manufacturing processes of the filter. Numerical and experimental investigations based on a 5-GHz band CPW HTS filter confirm that T-form structure suppresses the fluctuation to a level lower than the existing structure. The fabricated filter has a center frequency of 5.006 GHz, a 3.5% (175 MHz) equal ripple bandwidth, a 0.11-dB ripple, and a 0.11-dB average insertion loss, all measured at 60 K.