Fish-bone resonator with new coupling structure and its applications to wideband bandpass filters

In this paper, a novel fish-bone resonator is presented by cascading multiple cross-shaped resonators. Characterized by transmission line model analysis, it is found that the resonances of the proposed fish-bone resonator can be conveniently controlled, which results in a compact size. On the other hand, in order to constructed wideband bandpass filter, a novel coupling structure is studied in connection with the special configuration of the fish-bone resonator. Besides, transmission zeros are generated by the proposed fish-bone resonator, thus an ultra-wide stopband is achieved. To illustrate the concept, a wideband bandpass filter with high performance is constructed and measured by two-stage fish-bone resonators. The measured results are in good agreement with the full-wave simulation results. Both simulated and measured results are in good agreement to verify the predicted results.