A Simple Planar Dual-Band Bandpass Filter With Multiple Transmission Poles and Zeros

作者:Wu, Yongle*; Cui, Liwei; Zhuang, Zheng; Wang, Weimin; Liu, Yuanan
来源:IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS, 2018, 65(1): 56-60.
DOI:10.1109/TCSII.2017.2702191

摘要

A simple and planar design structure for dual-band bandpass filter (BPF) with multiple transmission poles and zeros is proposed in this brief. According to frequency response transformation, two passbands are realized on both sides of the operation frequency. Sharp selectivity and high isolation level with eight transmission poles and seven transmission zeros are achieved just by employing three-section coupled lines and three short-circuit stubs. Besides, the analytical (closed-form) extraction process for the transmission poles and zeros of the proposed dual-band BPF is presented based on the rigorous scattering-parameters theory and the even-and odd-mode analysis method. A prototype for the dual-band BPF with 3-dB fractional bandwidth of 41.1% and 19.0% is designed and fabricated. The measured and simulated results are in good agreement to verify the validity of the proposed design principle.