Design of triple-bandpass filters using an asymmetric stepped-impedance ring resonator

• Main Authors: Wang, Wensong, Chen, Yinchao, You, Li, Cao, Qunsheng, Yang, Shuhui
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2018
• Subjects: Resonators; Asymmetric; DRNTU::Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/89256; http://hdl.handle.net/10220/46157; http://www.jpier.org/PIERL/pierl67/02.17011605.pdf
• Institution: Nanyang Technological University

An asymmetric stepped-impedance ring resonator (ASIRR) is proposed for the design of a triple-bandpass filter. This resonator is applied to create the former two passbands by utilizing a stepped-impedance circular ring and the third passband by introducing two asymmetric coupling structures. It is found that the S-parameter performance can be improved by adding a pair of shorted and open stubs, and the second passband and the stopbands on both sides of the third passband can be tuned by adjusting the length of open stubs. A prototype filter operating at 1.04, 3.52 and 5.57 GHz is designed, fabricated, and measured with the corresponding fractional bandwidths of 23.1%, 7.4%, and 4.1%. Good agreements between the simulated and measured results are achieved for the ASIRR filter. Also, four transmission zeros are generated.