PIER Letters
Progress In Electromagnetics Research Letters
ISSN: 1937-6480
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By W. Wang, Y. Li, Q. Cao, S. Yang, and Y. Chen

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An asymmetric stepped-impedance ring resonator (ASIRR) is proposed for the design of a triple-bandpass filter. This resonator is applied to creat 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, 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.

W. Wang, Y. Li, Q. Cao, S. Yang, and Y. Chen, "Design of Triple-Bandpass Filters Using an Asymmetric Stepped-Impedance Ring Resonator," Progress In Electromagnetics Research Letters, Vol. 67, 7-12, 2017.

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