In this paper, a compact tri-band bandpass filter (BPF) using multi-stub-loaded resonator with controllable frequencies is presented. The multi-stub-loaded resonator consists of a main transmission line, two open stubs and a short stub. Characterized by using even- and odd-mode analysis, it is found that the resonator consists three modes, and the modes can be controlled individually, which enables convenient designs of tri-band BPFs. To demonstrate the proposed idea, a tri-band BPF with operating frequencies of 2.45, 3.8 and 5.15 GHz is implemented. Five transmission zeros are generated near the passband edges, resulting in high skirt selectivity. The total size of the filter is 0.19λg × 0.13λg, featuring compact size. The comparisons of the measured and simulated results are presented to validate the theoretical predications.
"Novel Compact Tri-Band Bandpass Filter Using Multi-Stub-Loaded Resonator," Progress In Electromagnetics Research C,
Vol. 50, 139-145, 2014. doi:10.2528/PIERC14041504
1. Jun, S. and K. Chang, "Compact microstrip bandpass filter using miniaturized hairpin resonator," Progress In Electromagnetics Research Letters, Vol. 37, 65-71, 2013.
2. Dai, G.-L. and M.-Y. Xia, "Novel miniaturized bandpass filters using spiral-shaped resonators and indow feed structures," Progress In Electromagnetics Research, Vol. 100, 235-243, 2010.
3. Wei, X., P. Wang, and Y. Shi, "Compact mixed-cross coupled bandpass filter with enhanced requency selectivity," Progress In Electromagnetics Research Letters, Vol. 37, 73-82, 2013.
4. Chaudhary, G., Y. Jeong, and J. Lim, "Dual-band bandpass fiter with independently tunable center frequencies and bandwidths," IEEE Trans. Microw. Theory Tech., Vol. 61, 107-116, 2013.
5. Zhang, R. and L. Zhu, "Design of a compact dual-band bandpass filter using coupled stepped-impedance resonators," IEEE Microw. Wireless. Compon. Lett., Vol. 24, No. 3, 155-157, 2014.
6. Gao, L. and X. Y. Zhang, "High selectivity dual-band bandpass filter using a quad-mode resonator with source-load coupling," IEEE Microw. Wireless. Compon. Lett., Vol. 23, No. 9, 474-476, 2013.
7. Zhang, S. and L. Zhu, "Compact tri-band bandpass filter based on λ/4 resonators with U-folded coupled-line," IEEE Microw. Wireless. Compon. Lett., Vol. 23, No. 5, 258-260, 2013.
8. Chen, F. C. and Q. X. Chu, "Design of compact tri-band bandpass filters using assembled resonators," IEEE Trans. Microw. Theory Tech., Vol. 57, 165-171, 2009.
9. Xu, K., Y. Zhang, D. Li, Y. Fan, J. L.-W. Li, W. T. Joine, and Q. H. Liu, "Novel design of a compact triple-band bandpass ¯lter using short stub-loaded SIRs and embedded SIRs structure," Progress In Electromagnetics Research, Vol. 142, 309-320, 2013.
10. Peng, Y., L. Zhang, Y. Leng, and J. Guan, "A compact tri-band passband filter based on three embedded bending stub resonators," Progress In Electromagnetics Research Letters, Vol. 37, 189-197, 2013.
12. Liu, B. and Y. Zhao, "Compact tri-band bandpass filter for WLAN and WiMAX using tri-section tepped-impedance resonators," Progress In Electromagnetics Research Letters, Vol. 45, 39-44, 2014.
13. Li, J., S. S. Huang, and J. Z. Zhao, "Design of a compact and high selectivity tri-band bandpass filter using asymmetric stepped-impedance resonators (SIRs)," Progress In Electromagnetics Research Letters, Vol. 44, 81-86, 2014.
14. Chen, F. C., Q. X. Chu, and Z.-H. Tu, "Tri-band bandpass filter using stub loaded resonators," Electron. Lett., Vol. 44, No. 12, 747-749, 2008.
15. Xue, S. J., L. Gao, and X. Y. Zhan, "Miniaturized tri-band bandpass filter using short-stub-loaded resonator with high selectivity," Micorw. Opt. Tech. Lett., Vol. 55, No. 9, 2081-2083, 2013.
16. Chen, W.-Y., M.-H. Weng, and S.-H. Chang, "A new tri-band bandpass filter based on stub-loaded step-impedance resonator," IEEE Microw. Wireless Compon. Lett., Vol. 22, No. 4, 179-181, 2012.
17. Liu, H.-W., Y. Wang, X.-M. Wang, J.-H. Lei, W.-Y. Xu, Y.-L. Zhao, B.-P. Ren, and X.-H. Guan, "Compact and high selectivity tri-band bandpass filter using multimode stepped-mpedance resonator," IEEE Microw. Wireless. Compon. Lett., Vol. 23, No. 10, 536-538, 2013.