A multi-stub-loaded resonator is presented in this paper. The resonators can be conveniently applied to design high-order dual-band bandpass filters (BPFs). Base on the analysis of the resonator, the first two even-mode resonant frequencies are controlled independently by the lengths of the loaded stubs. Two high-order dual-band BPFs using the first two even-mode resonant frequencies of the multi-stub-loaded resonators are proposed. The bandwidth of each passband can be adjusted independently by the coupling strength of the adjacent resonators. This paper deals with the analysis and design of the proposed high-order dual-band BPFs as well as the experimental validations of the predicted dual-band performance.
2. Weng, M.-H., C.-H. Kao, and Y.-C. Chang, "A compact dual-band bandpass filter using cross-coupled asymmetric SIRs for WLANs," Journal of Electromagnetic Waves and Application, Vol. 24, No. 2-3, 161-168, 2010.
3. Ma, D.-C., Z.-Y. Xiao, L.-L. Xiang, X.-H. Wu, C.-Y. Huang, and X. Kou, "Compact dual-band bandpass filter using folded SIR with two stubs for WLAN," Progress In Electromagnetic Research, Vol. 117, 357-364, 2011.
4. Weng, M. H., H. W. Wu, and Y. K. Su, "Compact and low loss dual-band bandpass filter using pseudo-interdigital stepped impedance resonators for WLANs," IEEE Microw. Wireless Compon. Lett., Vol. 17, No. 3, 187-189, Mar. 2007.
5. Wu, Y.-L. , C. Liao, and X.-Z. Xiong, "A dual-wideband bandpass filter based on E-shaped microstrip SIR with improved upper-stopband performance," Progress In Electromagnetics Research, Vol. 108, 141-153, 2010.
6. Zhang, X. Y., J. X. Chen, and Q. Xue, "Dual-band bandpass filter using stub-loaded resonators," IEEE Microw. Wireless Compon. Lett., Vol. 17, No. 8, 583-585, Aug. 2007.
7. Deng, H.-W., Y.-J. Zhao, X.-S. Zhang, L. Zhang, and W. Zhao, "Compact dual-mode open stub-loaded resonator and BPF," Progress In Electromagnetics Research Letters, Vol. 14, 119-125, 2010.
8. Chen, F. C., Q. X. Chu, and Z. H. Tu, "Design of compact dual-band bandpass filter using short stub loaded resonator," Microw. Opt. Technol. Lett., Vol. 51, No. 4, 959-963, Apr. 2009.
9. Chang, W. S. and C. Y. Chang, "Analytical design of microstrip short-circuit terminated stepped-impedance resonator dual-band ¯lters," IEEE Trans. Microw. Theory Tech., Vol. 59, No. 7, 1730-1739, Jul. 2011.
10. 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.
11. Zhang, Y. P. and M. Sun, "Dual-band microstrip bandpass filter using stepped-impedance resonators with new coupling schemes," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 10, 3779-3785, Oct. 2006.
12. Hong, J. S. and M. J. Lancaster, Microstrip Filter for RF/Microwave Applications, Wiley, New York, 2001.