A Low-Loss 5 GHz Bandpass Filter Using HTS Quarter-Wavelength Coplanar Waveguide Resonators

Hideyuki SUZUKI  Zhewang MA  Yoshio KOBAYASHI  Kei SATOH  Shoichi NARAHASHI  Toshio NOJIMA  

IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.3   pp.714-719
Publication Date: 2002/03/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Superconductive Electronics)
Category: Microwave Devices and Systems
superconductor,  coplanar waveguide,  quarter-wavelength resonator,  band-pass filter,  microwave,  

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A new structure of a low-loss high temperature superconducting (HTS) filter is proposed by using quarter-wavelength coplanar waveguide (CPW) resonators. A 4-pole Chebyshev band-pass filter with the center frequency 5.0 GHz and the 0.01 dB-ripple fractional bandwidth 3.2% is designed based on the theory of direct-coupled resonator filters using K- and J-inverters. This filter is fabricated by using a high-Tc superconductive YBCO film deposited on a MgO dielectric substrate. The frequency response of the filter measured at 60 K agrees very well with the theoretical one. The insertion loss is 0.22 dB. The insertion loss of this filter is the lowest in HTS-CPW filters presented so far.