This letter presents a dual-wideband bandpass filter (BPF) by using open and shorted stubs loaded ring resonator. The resonator can excite multiple resonant modes. The transmission zeros (TZs) analyzed by the transversal signal interference concepts can divide the resonant modes into two groups that form dual-wide passband. The even-mode resonant frequencies can be controlled by the stubs parameters, and the TZs can be tuned by the port angle independently. So the center frequency (CF) and the bandwidth of each passband can be flexibly controlled. An experimental dual-wideband BPF with CF of 1.48/5.7 GHz and 3 dB FBW of 137.8%/49.3% is implemented, and the experimental results are presented for validation.
2. Xu, J., Y.-X. Ji, C. Miao, and W. Wu, "Compact single-/dual-wideband BPF using stubs loaded SIR (SsLSIR)," IEEE Microw. Wireless Compon. Lett., Vol. 23, No. 7, 338-340, Jul. 2013.
doi:10.1109/LMWC.2013.2263220
3. Xu, J., W. Wu, and C. Miao, "Compact microstrip dual-/tri-/quad-band bandpass filter using open stubs loaded shorted stepped-impedance resonator," IEEE Trans. Microw. Theory Tech., Vol. 61, No. 3, 3187-3199, Sep. 2013.
doi:10.1109/TMTT.2013.2273759
4. Li, J., S.-S. Huang, and J.-Z. Zhao, "Compact dual-wideband bandpass filter using a novel penta-mode resonator (PMR)," IEEE Microw. Wireless Compon. Lett., Vol. 24, No. 10, 668-670, Oct. 2014.
doi:10.1109/LMWC.2014.2341014
5. Li, J., S.-S. Huang, H. Wang, and J.-Z. Zhao, "A novel compact dual-wideband bandpass filter with multi-mode resonators," Progress In Electromagnetics Research Letters, Vol. 51, 79-85, 2015.
doi:10.2528/PIERL14122302
6. Kuo, J.-T., C.-Y. Fan, and S.-C. Tang, "Dual-wideband bandpass filters with extended stopband based on coupled-line and coupled three-line resonators," Progress In Electromagnetics Research, Vol. 124, 1-15, 2012.
doi:10.2528/PIER11120103
7. Sanchez-Soriano, M. A. and R. Gomez-Garcia, "Sharp-rejection wide-band dual-band bandpass planar filters with broadly-separated passbands," IEEE Microw. Wireless Compon. Lett., Vol. 25, No. 2, 97-99, Feb. 2015.
doi:10.1109/LMWC.2014.2382669
8. Wu, Y.-L., C. Liao, and X.-Z. Xiong, "A dual-wideband bandpass filters baded on E-shaped microstrip SIR with improved upper-stopband performance," Progress In Electromagnetics Research, Vol. 108, 141-153, 2010.
doi:10.2528/PIER10071802
9. Wang, X.-H., B.-Z. Wang, and K. J. Chen, "Compact broadband dual-band bandpass filters using slotted ground structures," Progress In Electromagnetics Research, Vol. 82, 151-166, 2008.
doi:10.2528/PIER08030101
10. Feng, W.-J., W.-Q. Che, Y.-M. Chang, S.-Y. Shi, and Q. Xue, "High selectivity fifth-order wideband bandpass filters with multiple transmission zeros based on transversal signal-interactrion concepts," IEEE Trans. Microw. Theory Tech., Vol. 61, No. 1, 87-97, Jan. 2013.
doi:10.1109/TMTT.2012.2227785