New CPW Quarter-Wavelength Resonator with Open Stubs for Multipole Dual-Band Bandpass Filter

This paper proposes a newly developed CPW quarter-wavelength resonator with open stubs for use in a multipole dual-band bandpass filter. The proposed resonator has odd- and even-mode resonant frequencies that are configured using the space between the center conductor and the open stubs. It is easy to configure independently the odd- and even-mode coupling coefficients because the two resonant modes have different current density distributions. We design and fabricate a four-pole Chebyshev 2.0-/3.5-GHz band bandpass filter to investigate the validity of the proposed resonator. The proposed resonator is suitable for use in a multipole dual-band bandpass filter.