Design of dual/tri-band BPF with controllable bandwidth based on a quintuple-mode resonator

Abstract

—In this article, a new class of dual-/tri-band bandpass filters (BPFs) using a quintuple-mode resonator (QMR) is proposed. The classic odd-/even-mode analysis method is used to analyze the two filters due to their symmetrical structure. Owing to characteristics of the QMR, the dual/tri-band BPFs based on the same topology are designed. The bandwidths (BWs) of the passbands are controllable. A dual-band BPF with center frequencies of 2.1 GHz/3.43 GHz and a tri-band BPF with center frequencies of 2.35 GHz/3.44 GHz/5.2 GHz are designed, fabricated, and measured. The fabricated filters are compact in size, and measured results are in good agreement with the simulated ones.