A high selectivity dual-band bandpass filter using quadruple-mode multi-stub loaded ring resonator (SLRR)

摘要

A high selectivity dual-band filter is proposed based on the quadruple-modemulti-stub loaded ring resonator. The ring resonator can utmostly avoid bendingthe electromagnetic wave. Two external open stubs are employed to generatefour transmission poles where the odd- and even-mode is utilized toanalyze the resonant frequencies of the BPF. The internal stub effectivelyreduces the insert loss (IL) by improving the external quality factor Q_e of thesecond passband. In addition, five transmission zeros are generated due to themultipath and self-resonance modes to improve the out-of-band selectivity ofthe proposed filter. The proposed filter centered at 2.65 and 4.84 GHz isdesigned, fabricated and measured. The simulated results agree well with themeasured results.