Dual-mode stub-loaded resonator and its applications to single- and dual-band bandpass filters

摘要

In this letter, a novel dual-mode stub-loaded resonator is proposed with independently controllable coupling coefficients under different resonant modes. The main structure is constructed by loading a short-circuited stub in the center of an open-loop half-wavelength resonator. Frequencies of first and second resonant modes can be adjusted by changing the dimensions of the loaded stub and open-loop resonator, respectively. Additionally, a pair of edge-coupled ear-structures is added to adjust the difference between the coupling coefficients of different resonant modes. Finally, a dual-band bandpass filter (BPF) with independently controllable bandwidths as well as a single-band BPF with high selectivity are designed and fabricated to provide experimental validations on the predicted performances of the proposed filters. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:623-626, 2016