volume | PIER Journals

Abstract

This paper proposes a new compact quad-channel diplexer (2.45/4.2 GHz and 3.5/5.2 GHz) using defected stepped impedance resonators (DSIRs). The proposed quad-channel diplexer is composed of one common input feeding line, sixteen folded DSIRs, and two output feeding lines. Every four DSIRs are designed to determine passband characteristics of one individual channel, and two passbands are filtered out eventually at each output port. The distributed coupling technique featured by small loading effect is introduced to eliminate the necessity of extra impedance matching networks, which consequently results in a reduced circuit size. A diplexer prototype operated at 2.45/4.2 GHz and 3.5/5.2 GHz bands with measured 3-dB fractional bandwidths of 12.5%, 7.2%, 6.4%, and 5.0% has been implemented, showing a high isolation of larger than 33 dB between the two output ports. Experimental results coincide well with the theoretical predictions and simulation results.

1. Pozar, D. M., Microwave Engineering, John Wiley & Sons, 1998.

2. Yang, T., P. L. Chi, and T. Itoh, "High isolation and compact diplexer using the hybrid resonators," IEEE Microwave Wireless Compon. Lett., Vol. 20, No. 10, 551-3, 2010.
doi:10.1109/LMWC.2010.2052793

3. Shi, J., J.-X. Chen, and Z.-H. Bao, "Diplexers based on microstrip line resonators with loaded elements," Progress In Electromagnetics Research, Vol. 115, 423-439, 2011.
doi:10.2528/PIER11031516

4. Chen, C. F., T. Y. Huang, C. P. Chou, and R. B. Wu, "Microstrip diplexers design with common resonator sections for compact size, but high isolation," IEEE Trans. Microwave Theory Tech., Vol. 54, No. 5, 1945-52, 2006.
doi:10.1109/TMTT.2006.873613

5. Chuang, M. L. and M. T. Wu, "Microstrip diplexer design using common T-shaped resonator," IEEE Microwave Wireless Compon. Lett., Vol. 21, No. 11, 583-5, 2011.
doi:10.1109/LMWC.2011.2168949

6. Hong, S. and K. Chang, "A 10-35-GHz six-channel microstrip multiplexer for wide-band communication systems," IEEE Trans. Microwave Theory Tech., Vol. 54, No. 4, 1370-8, 2006.
doi:10.1109/TMTT.2006.871912

7. Makimoto, M. and S. Yamashita, "Bandpass filters using parallel coupled stripline stepped impedance resonators," IEEE Trans. Microwave Theory Tech., Vol. 28, No. 12, 1413-7, 1980.
doi:10.1109/TMTT.1980.1130258

8. Wei, F., P. Y. Qin, Y. J. Guo, and X. W. Shi, "Design of multi-band bandpass filters based on stub loaded stepped-impedance resonator with defected microstrip structure," IET Microw. Antennas Propag., Vol. 10, No. 2, 230-6, 2016.
doi:10.1049/iet-map.2015.0495

9. Ai, J., Y. H. Zhang, K. D. Xu, D. T. Li, and Q. H. Liu, "Design of a high-selectivity quad-band bandpass filter based on λ/4 resonators with alternative J/K inverters," Int. J. Electron. Commun., Vol. 70, No. 8, 1028-33, 2016.
doi:10.1016/j.aeue.2016.04.019

10. Wu, H. W., S. H. Huang, and Y. F. Chen, "Design of new quad-channel diplexer with compact circuit size," IEEE Microwave Wireless Compon. Lett., Vol. 23, No. 5, 240-2, 2013.
doi:10.1109/LMWC.2013.2253314

11. Hsu, K. W., W. C. Hung, and W. H. Tu, "Design of four-channel diplexer using distributed coupling technique," Microwave Opt. Technol. Lett., Vol. 58, No. 1, 166-70, 2016.
doi:10.1002/mop.29516

12. Tu, W. H. and W. C. Hung, "Microstrip eight-channel diplexer with wide stopband," IEEE Microwave Wireless Compon. Lett., Vol. 24, No. 11, 742-4, 2014.
doi:10.1109/LMWC.2014.2348499

13. Deepak, U., T. K. Roshna, C. M. Nijas, K. Vasudevan, and P. Mohanan, "A dual band SIR coupled dipole antenna for 2.4/5.2/5.8 GHz applications," IEEE Trans. Antennas Propag., Vol. 63, No. 4, 1514-20, 2015.
doi:10.1109/TAP.2015.2393876

14. Sagawa, M., M. Makimoto, and S. Yamashita, "Geometrical structures and fundamental characteristics of microwave stepped-impedance resonators," IEEE Trans. Microwave Theory Tech., Vol. 45, No. 7, 1078-85, 1997.
doi:10.1109/22.598444

15. Liu, H. W., W. Y. Xu, Z. C. Zhang, and X. H. Guan, "Compact diplexer using slotline stepped impedance resonator," IEEE Microw. Wireless Compon. Lett., Vol. 23, No. 2, 75-7, 2013.
doi:10.1109/LMWC.2013.2238912

16. Wen, P. H., C. I. G. Hsu, C. H. Lee, and H. H. Chen, "Design of balanced and balun diplexers using stepped-impedance slot-line resonator," J. Electromagn. Waves Appl., Vol. 28, No. 6, 700-15, 2014.
doi:10.1080/09205071.2014.885398

17. Hong, J. S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, John Wiley & Sons, 2001.
doi:10.1002/0471221619

18. Li, Z.-P., L.-J. Zhang, T. Su, and C.-H. Liang, "A compact microstrip quadruplexer using slotline stepped impedance stub loaded resonators," Progress In Electromagnetics Research, Vol. 140, 509-522, 2013.
doi:10.2528/PIER13042105

Dr. Anfu Zhu

Dr. Haidong Zhou

Dr. Jianzhong Chen

Professor Jianxing Li