volume | PIER Journals

Abstract

A dual-mode dual-band bandpass filter is designed using a single stub-loaded slot ring resonator. This resonator is coupled to the two external feed lines at two positions spaced at 135° along the slot ring through a pair of microstrip-slotline Tjunctions. With a proper choice of the degree of external coupling, the first-order degenerate modes are split to make up the first passband with two transmission poles. The second passband is realized by the second-order degenerate modes, which are stimulated by symmetrically attaching four identical stubs along the slot ring. The center frequency ratio of the two operating passbands is controlled by the nature and strength of the external coupling, which is determined by the characteristics of the microstrip opencircuited stubs. Finally, a dual-band filter with center frequencies at 2.4 and 5.2 GHz is designed and fabricated. Measured results verify the design principle and predicted dual-passband performance. Benefiting from an additional transmission zero brought by the transitions, the upper stopband is expanded up to 12.75 GHz with at least 13 dB of rejection.

1. Chen, J. X., T. Y. Yum, J.-L. Li, and Q. Xue, "Dual-mode dual-band bandpass filter using stacked-loop structure," IEEE Microw. Wireless Compon. Lett., Vol. 16, No. 9, 502-504, 2006.
doi:10.1109/LMWC.2006.880705

2. Zhang, X. Y. and Q. Xue, "Novel dual-mode dual-band filters using coplanar-waveguide-fed ring resonators," IEEE Trans. Microw. Theory Tech., Vol. 55, No. 10, 2183-2190, 2007.
doi:10.1109/TMTT.2007.906501

3. Gorur, A. and C. Karpuz, "Compact dual-band bandpass filters using dual-mode resonators," IEEE MTT-S Int. Microwave Symp., 905-908, Honolulu, USA, Jun. 2007.

4. Djoumessi, E. E. and K. Wu, "Multilayer dual-mode dual-bandpass filter," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 1, 21-23, 2009.
doi:10.1109/LMWC.2008.2008552

5. Baik, J.-W., L. Zhu, and Y.-S. Kim, "Dual-mode dual-band bandpass filter using balun structure for single substrate configuration," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 11, 613-615, 2010.
doi:10.1109/LMWC.2010.2060184

6. Chen, Z.-X., X.-W. Dai, and C.-H. Liang, "Novel dual-mode dual-band bandpass filter using double square-loop structure," Progress In Electromagnetics Research, Vol. 77, , 409-416, 2007.
doi:10.2528/PIER07082803

7. Huang, T.-H., H.-J. Chen, C.-S. Chang, L.-S. Chen, Y.-H. Wang, and M.-P. Houng, "A novel compact ring dual-mode filter with adjustable second-passband for dual-band applications," IEEE Microw. Wireless Compon. Lett., Vol. 16, No. 6, 360-362, 2006.
doi:10.1109/LMWC.2006.875607

8. Chiou, Y.-C., P.-S. Yang, J.-T. Kuo, and C.-Y.Wu, "Transmission zeros 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

9. Chiou, Y.-C., C.-Y. Wu, and J.-T. Kuo, "New miniaturized dual-mode dual-band ring resonator bandpass filter with microwave C-sections," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 2, 67-69, 2010.
doi:10.1109/LMWC.2009.2038432

10. Luo, S. and L. Zhu, "A novel dual-mode dual-band bandpass filter based on a single ring resonator," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 8, 497-499, 2009.
doi:10.1109/LMWC.2009.2024826

11. Luo, S., L. Zhu, and S. Sun, "A dual-mode dual-band bandpass filter using a single ring resonator," Proc. Asia-Pacific Microwave Conf., 921-924, Singapore, Dec. 2009.

12. Luo, S., L. Zhu, S. Sun, and , "A dual-band ring-resonator bandpass filter based on two pairs of degenerate modes," IEEE Trans. Microw. Theory Tech. , Vol. 58, No. 12, 3427-3432, 2010.

13. Gupta, K. C., R. Garg, I. Bahl, and P. Bhartia, Microstrip Lines and Slotlines, 2nd Ed., Artech House, 1996.

14. Advanced Design System (ADS) 2006a. Agilent Technol., Palo Alto, , CA, 2006.

Dr. Sha Luo

Professor Lei Zhu

Dr. Sheng Sun