A novel dual-band bandpass filter using nested quarter-mode substrate integrated waveguides

A novel dual-band bandpass filter using nested quarter-mode substrate integrated waveguides (QMSIW) is proposed. Two triangular QMSIW cavities of different size are nested one into another to provide a dual-resonance response. Compared to conventional dual-band SIW filters which utilize the multiple cavity modes, the proposed resonator features the advantages of compact circuit size and flexibility in controlling two resonant frequencies independently. In addition, due to the frequency-dependent mixed electric and magnetic coupling between the resonators, two transmission zeros can be observed between two passbands resulting in sharp passband selectivity and high band-to-band isolation.