This paper presents a wide upper stopband dual-band bandpass filter (BPF) with controllable passband frequencies and bandwidths as well as a high out-of-band rejection level. The proposed filter is realized by utilizing a novel stepped impedance stub-loaded quad-mode resonator. All the four-mode equivalent circuits of the resonator are quarter-wavelength stepped impedance resonators (SIRs), and their fundamental resonance frequencies are used to form the passbands, so the designed filter has a compact circuit size. By controlling the impedance and length ratios of the stubs of the resonator, wide upper stopband performance is obtained. Hook-shape feed-lines and source-load coupling are applied to provide appropriate external coupling and generate three extra transmission zeros, which greatly improve the selectivity of the proposed filter. An experimental filter operating at 1.5 and 3.5 GHz is designed, fabricated, and measured for validation. The measured results have good agreement with the simulated ones.
2. Kuo, J.-T. and S.-W. Lai, "New dual-band bandpass filter with wide upper rejection band," Progress In Electromagnetics Research, Vol. 123, 371-384, 2012.
doi:10.2528/PIER11112304
3. Mondal, P. and M. K. Mandal, "Design of dual-band bandpass filters using stub-loaded open-loop resonators," IEEE Trans. Microw. Theory Tech., Vol. 56, No. 1, 150-155, Jan. 2008.
doi:10.1109/TMTT.2007.912204
4. Wu, G.-L., W. Mu, X.-W. Dai, and Y.-C. Jiao, "Design of novel dual-band bandpass filter with microstrip meander-loop resonator and CSRR DGS," Progress In Electromagnetics Research, Vol. 78, 17-24, 2008.
doi:10.2528/PIER07090301
5. Zhang, X. Y., J.-X. Chen, Q. Xue, and S.-M. Li, "Dual-band bandpass filters using stub-loaded resonators," IEEE Microw. Wirel. Compon. Lett., Vol. 17, No. 8, 583-585, Aug. 2007.
doi:10.1109/LMWC.2007.901768
6. Kuo, J.-T., S.-C. Tang, and S.-H. Lin, "Quasi-elliptic function bandpass filter with upper stopband extension and high rejection level using cross-coupled stepped-impedance resonators," Progress In Electromagnetics Research, Vol. 114, 395-405, 2011.
doi:10.2528/PIER11011002
7. Ma, D., Z.-Y. Xiao, L. Xiang, X. Wu, C. Huang, and X. Kuo, "Compact dual-band bandpass filter using folded SIR with two stubs for WLAN," Progress In Electromagnetics Research, Vol. 117, 357-364, 2011.
doi:10.2528/PIER11040201
8. Zhou, M., X. Tang, and F. Xiao, "Compact dual band bandpass filter using novel E-type resonators with controllable bandwidths," IEEE Microw. Wirel. Compon. Lett., Vol. 18, No. 12, 779-781, Dec. 2008.
doi:10.1109/LMWC.2008.2007696
9. Yao, Z., C. Wang, and N. Y. Kim, "A compact dual-mode dual-band bandpass filter using stepped-impedance open-loop resonators and center-loaded resonators," Microw. Opt. Technol. Lett., Vol. 55, No. 12, 3000-3005, Dec. 2013.
10. Sun, S., "A dual-band bandpass filter using a single dual-mode ring resonator," IEEE Microw. Wirel. Compon. Lett., Vol. 21, No. 6, 298-300, Jun. 2011.
doi:10.1109/LMWC.2011.2132119
11. Sun, S.-J., B. Wu, T. Su, K. Deng, and C.-H. Liang, "Wideband dual-mode microstrip filter using short-ended resonators with centrally loaded inductive stub," IEEE Trans. Microw. Theory Tech., Vol. 60, No. 12, 3667-3673, Dec. 2012.
doi:10.1109/TMTT.2012.2221737
12. Hong, J. S. and H. Shaman, "Dual-mode microstrip open-loop resonators and filters," IEEE Trans. Microw. Theory Tech., Vol. 55, No. 8, 1764-1770, Aug. 2007.
doi:10.1109/TMTT.2007.901592
13. Fu, S., B.Wu, J. Chen, S.-J. Sun, and C. H. Liang, "Novel second-order dual-mode dual-band filters using capacitance loaded square loop resonator," IEEE Trans. Microw. Theory Tech., Vol. 60, No. 3, 477-483, Mar. 2012.
doi:10.1109/TMTT.2011.2181859
14. Li, Y.-C., H. Wong, and Q. Xue, "Dual-mode dual-band bandpass filter based on a stub-loaded patch resonator," IEEE Microw. Wirel. Compon. Lett., Vol. 21, No. 10, 525-527, Oct. 2011.
doi:10.1109/LMWC.2011.2164394
15. Sun, S.-J., T. Su, K. Deng, B. Wu, and C.-H. Liang, "Shorted-ended stepped-impedance dual-resonance resonator and its application to bandpass filters," IEEE Trans. Microw. Theory Tech., Vol. 61, No. 9, 3209-3215, Sep. 2013.
doi:10.1109/TMTT.2013.2273895
16. Luo, S. and L. Zhu, "A novel dual-mode dual-band bandpass filter based on a single ring resonator," IEEE Microw. Wirel. Compon. Lett., Vol. 19, No. 8, 497-499, Aug. 2009.
doi:10.1109/LMWC.2009.2024826
17. Sung, Y., "Dual-mode dual-band filter with band notch structures," IEEE Microw. Wirel. Compon. Lett., Vol. 20, No. 2, 73-75, Feb. 2010.
doi:10.1109/LMWC.2009.2038434
18. Chiou, Y.-C., P.-S. Yang, J.-T. Kuo, and C.-Y. Wu, "Transmission zero design graph for dual-mode dual-band filter with periodic stepped-impedance ring resonator," Progress In Electromagnetics Research, Vol. 108, 23-36, 2010.
doi:10.2528/PIER10071608
19. Zhao, L.-P., X.-W. Dai, Z.-X. Chen, and C.-H. Liang, "Novel design of dual-mode dual-band bandpass filter with triangular resonators," Progress In Electromagnetics Research, Vol. 77, 417-424, 2007.
doi:10.2528/PIER07090501
20. Kim, C. H. and K. Chang, "Independently controllable dual-band bandpass filters using asymmetric stepped-impedance resonators," IEEE Trans. Microw. Theory Tech., Vol. 59, No. 12, 3037-3047, Dec. 2011.
doi:10.1109/TMTT.2011.2168973
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