volume | PIER Journals

Abstract

In this letter, a novel, compact bandpass filter architecture that leverages a quadruple-mode stepped impedance resonator (SIR) is introduced. This design is predicated on the principles of odd-even-mode analysis, which has been meticulously applied twice to elucidate the resonator's operational dynamics. The distinct boundary conditions inherent to the odd-odd and even-odd degenerate modes result in their splitting, a phenomenon that is pivotal to the filter's performance characteristics. The equivalent circuits representing the quadruple modes function as quarter-wavelength SIRs, a design choice that inherently confers a compact form factor upon the resonator. This is achieved without compromising the filter's functionality, as each mode contributes to the overall filtering response in a manner that is both efficient and space-saving. Furthermore, the filter is characterized by a 20-dB stopband rejection that extends up to 6.9 GHz, which corresponds to 3.8 times of the fundamental frequency (f₀). This outstanding stopband performance is a testament to the design's effectiveness in attenuating unwanted signals while maintaining a compact footprint.

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Dr. Chuan Shao

Dr. Rong Cai

Dr. Xinnai Zhang

Dr. Kai Xu