volume | PIER Journals

Abstract

This paper presents a compact and novel coupling structure for diplexers and power dividers based exclusively on coupled resonators. It consists of two cross-coupled structures joined together by two common resonators with a cluster of only four resonators. For a diplexer, it represents one of the most compact topologies that produces two 2nd-order channel filters with two fully controllable transmission zeros. This can be used to increase the rejection and isolations between channels without increasing the number of resonators. The same topology can also be used to realise a 3rd-order filtering power divider (FPD), with its embedded cascade trisection (CT) structure generating an asymmetric transmission zero. The coupling matrices of several diplexers and power dividers have been synthesized. Two microstrip diplexers with different positions of the transmission zeros have been demonstrated to verify the device concept. A 1.8 GHz FPD with a fractional bandwidth of 5% has also been prototyped, showing an improved out-of-band rejection from 15 dB to 25 dB below 1.71 GHz. The isolation performance of the divider has been investigated and improved from 7 dB to 18 dB across the band by adding only one resistor.

1. Chuang, M. L. and M. T. Wu, "Microstrip diplexer design using common T-shaped resonator," IEEE Microw. Wireless Compon. Lett., Vol. 21, 583-585, 2011.
doi:10.1109/LMWC.2011.2168949 Google Scholar

2. Cameron, R. J. and M. Yu, "Design of manifold-coupled multiplexers," IEEE Microw. Mag., Vol. 8, 46-59, 2007.
doi:10.1109/MMM.2007.904715 Google Scholar

3. Wang, Y. and M. J. Lancaster, "An investigation on the coupling characteristics of a novel multiplexer configuration," Eur. Microw. Conf., 900-903, 2013. Google Scholar

4. Shang, X. B., Y. Wang, W. Xia, et al. "Novel multiplexer topologies based on all-resonator structures," IEEE Trans. Microw. Theory Tech., Vol. 61, 3838-3845, 2013.
doi:10.1109/TMTT.2013.2284496 Google Scholar

5. Macchiarella, G. and S. Tamiazzo, "Synthesis of star-junction multiplexers," IEEE Trans. Microw. Theory Tech., Vol. 58, 3732-3741, 2010. Google Scholar

6. Chuang, M. L. and M.-T. Wu, "Microstrip diplexer design using common T-shaped resonator," IEEE Microw. Wireless Compon. Lett., Vol. 21, 583-585, 2011.
doi:10.1109/LMWC.2011.2168949 Google Scholar

7. Wang, X., J.Wang, and G. Zhang, "Design of wideband filtering power divider with high selectivity and good isolation," Electron. Lett., Vol. 52, 1389-1391, 2016.
doi:10.1049/el.2016.2065 Google Scholar

8. Shao, J. Y., S. C. Huang, and Y. H. Pang, "Wilkinson power divider incorporating quasi-elliptic filters for improved out-of-band rejection," Electron. Lett., Vol. 47, 1288-1289, 2011.
doi:10.1049/el.2011.2766 Google Scholar

9. Chen, C. F., T. Y. Huang, T. M. Shen, et al. "Design of miniaturized filtering power dividers for system-in-a-package," IEEE Trans. Compon. Packag. Technol., Vol. 3, 1663-1672, 2013.
doi:10.1109/TCPMT.2013.2254488 Google Scholar

10. Li, Q., Y. Zhang, and Y. Fan, "Dual-band in-phase filtering power dividers integrated with stubloaded resonators," IET Microw. Anten. Propag., Vol. 9, 695-699, 2015.
doi:10.1049/iet-map.2014.0487 Google Scholar

11. Li, Y. C., Q. Xue, and X. Y. Zhang, "Single- and dual-band power dividers integrated with bandpass filters," IEEE Trans. Microw. Theory Tech., Vol. 61, 69-76, 2013.
doi:10.1109/TMTT.2012.2226600 Google Scholar

12. Avrillon, S., I. Pele, A. Chousseaud, et al. "Dual-band power divider based on semiloop steppedimpedance resonators," IEEE Trans. Microw. Theory Tech., Vol. 51, 1269-1273, 2003.
doi:10.1109/TMTT.2003.809667 Google Scholar

13. Uchida, H., N. Yoneda, Y. Konishi, et al. "Bandpass directional couplers with electromagneticallycoupled resonators," 2006 IEEE MTT-S Int. Microw. Symp. Digest, 1563-1566, 2006.
doi:10.1109/MWSYM.2006.249613 Google Scholar

14. Scardelletti, M. C., G. E. Ponchak, and T. M. Weller, "Miniaturized Wilkinson power dividers utilizing capacitive loading," IEEE Microw. Wireless Compon. Lett., Vol. 12, 6-8, 2002.
doi:10.1109/7260.975717 Google Scholar

15. Mirzavand, R., M. M. Honari, A. Abdipour, et al. "Compact microstrip wilkinson power dividers with harmonic suppression and arbitrary power division ratios," IEEE Trans. Microw. Theory Tech., Vol. 61, 61-68, 2013.
doi:10.1109/TMTT.2012.2226054 Google Scholar

16. Miao, C., J. Yang, G. Tian, X. Zheng, et al. "Novel sub-miniaturized wilkinson power divider based on small phase delay," IEEE Microw. Wireless Compon. Lett., Vol. 24, 662-664, 2014.
doi:10.1109/LMWC.2014.2340580 Google Scholar

17. Yu, X. and S. Sun, "Synthesis of filtering power divider with complex source and load impedances," 2016 IEEE Int. Symp. Antennas and Propagation (APSURSI), 1719-1720, 2016.
doi:10.1109/APS.2016.7696566 Google Scholar

18. Skaik, T. F., M. J. Lancaster, and F. Huang, "Synthesis of multiple output coupled resonator circuits using coupling matrix optimisation," IET Microw. Antennas Propag., Vol. 5, 1081-1088, 2011.
doi:10.1049/iet-map.2010.0447 Google Scholar

19. Deng, Y., J. Wang, L. Zhu, et al. "Filtering power divider with good isolation performance and harmonic suppression," IEEE Microw. Wireless Compon. Lett., Vol. 26, 984-986, 2016.
doi:10.1109/LMWC.2016.2623244 Google Scholar

20. Chen, C. F. and C. Y. Lin, "Compact microstrip filtering power dividers with good in-band isolation performance," IEEE Microw. Wireless Compon. Lett., Vol. 24, 17-19, 2014.
doi:10.1109/LMWC.2013.2287243 Google Scholar

21. Hong, J. S. and M. J. Lancaster, "Microstrip cross-coupled trisection bandpass filters with asymmetric frequency characteristics," Proc. Inst. Elect. Eng., Vol. 146, 84-90, 1999. Google Scholar

22. Zhang, X. Y., K. X. Wang, and B. J. Hu, "Compact filtering power divider with enhanced secondharmonic suppression," IEEE Microw. Wireless Compon. Lett., Vol. 23, 483-485, 2013.
doi:10.1109/LMWC.2013.2274993 Google Scholar

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

Dr. Yun Wu

Dr. Ruiheng Wu

Dr. Yi Wang