A compact and high‐selectivity tri‐band bandpass filter based on symmetrical stub‐loaded square ring resonator. Issue 2 (17th October 2019)

• Record Type: Journal Article
• Authors: Liu, Liang; Liang, Xianling; Jin, Ronghong; Bai, Xudong; Fan, Haijun; Geng, Junping
• Is Part Of: Microwave and optical technology letters. Volume 62:Issue 2(2020:Feb.)
• Page Start: 630
• Page End: 636
• Publication Date: 2019-10-17
• Subjects: compact size -- high selectivity -- odd‐ and even‐mode analysis -- symmetrical stub‐loaded square ring resonator -- tri‐band bandpass filter; Microwaves -- Periodicals; Optics -- Periodicals; 621
• DOI: 10.1002/mop.32070
• Languages: English
• ISSNs: 0895-2477

Abstract

Abstract: A compact tri‐band bandpass filter is presented in this article, whose three passbands are realized by the lowest three resonant modes of a new structure of symmetrical stub‐loaded square ring resonator. The filter features a compact size of 0.049 λ g 2 ( λ g is the guided wavelength) as well as a high selectivity with nine transmission zeros. In addition, by using the odd‐ and even‐mode analysis, its center frequencies can be easily tuned to the desired frequencies by the identical‐number parameters, namely, the lengths of short‐, open‐, and square ring‐stubs. To validate the proposed design, a tri‐band bandpass filter with center frequencies of 2.4, 3.5, and 5.2 GHz was designed, simulated, and measured. The measurement results agree well with the simulation results.