volume | PIER Journals

Abstract

This paper presents an approach to the design of novel diplexers with pairs of transmission zeros for each output port. A rotationally symmetric structure with shorted circuited stubs is proposed to achieve diplexer operation, and the diplexer exhibits a good filtering performance with a pair of transmission zeros allocated at two sides of the passbands as well. The analysis of the rotationally symmetric structure bandpass filter is also presented in this paper in detail. Moreover, the interdigital coupled-lines are introduced to improve the out-of-band performance of the proposed rotationally symmetric diplexer. In order to verify the proposed structure, first a diplexer with rotationally structure operating at 2.4/2.73 GHz with simulated insertion loss of 1.217/0.930 dB is designed and simulated, then a diplexer with interdigital coupled-lines operating at 5/5.8 GHz with measured insertion loss of 1.524/1.524 dB is designed, simulated and measured to improve the passband selectivity, and the measured results are in good agreement with simulated ones.

1. Sze, J.-Y., T.-H. Hu, and T.-J. Chen, "Compact dual-band annular-ring slot antenna with meandered grounded strip," Progress In Electromagnetics Research, Vol. 95, 299-308, 2009.
doi:10.2528/PIER09072404 Google Scholar

2. Shi, L., H.-J. Sun, W.-W. Dong, and X. Lv, "A dual-band multi-function carborne hybrid antenna for satellite communication relay system," Progress In Electromagnetics Research, Vol. 95, 329-340, 2009.
doi:10.2528/PIER09070306 Google Scholar

3. Behera, S. and K. J. Vinoy, "Microstrip square ring antenna for dual-band operation," Progress In Electromagnetics Research, Vol. 93, 41-56, 2009.
doi:10.2528/PIER09021909 Google Scholar

4. Tilanthe, P., P. C. Sharma, and T. K. Bandopadhyay, "A monopole microstrip antenna with enhanced dual band rejection for UWB application," Progress In Electromagnetics Research B, Vol. 38, 315-331, 2012. Google Scholar

5. Wang, X.-H., B.-Z. Wang, and K. J. Chen, "Compact broadband dual-band bandpass filters using slotted ground structures," Progress In Electromagnetics Research, Vol. 82, 151-166, 2008.
doi:10.2528/PIER08030101 Google Scholar

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 Google Scholar

7. Patin, J. M., N. R. Labadie, and S. K. Sharma, "Investigations on an H-fractal wideband microstrip filter with multi-passbands and a tuned notch band," Progress In Electromagnetics Research B, Vol. 22, 285-303, 2010.
doi:10.2528/PIERB10041001 Google Scholar

8. Chen, M., Y.-C. Lin, and M.-H. Ho, "Quasi-lumped design of bandpass filter using combined CPW and microstrip," Progress In Electromagnetics Research Letters, Vol. 9, 59-66, 2009.
doi:10.2528/PIERL09042201 Google Scholar

9. Wu, Y., Y. Liu, and S. Li, "A compact pi-structure dual band transformer," Progress In Electromagnetics Research, Vol. 88, 121-134, 2008.
doi:10.2528/PIER08102601 Google Scholar

10. Castaldi, G., V. Fiumara, and I. Gallina, "An exact synthesis method for dual-band chebyshev impedance transformers," Progress In Electromagnetics Research, Vol. 88, 305-319, 2008.
doi:10.2528/PIER08100605 Google Scholar

11. Strassner, B. and K. Chang, "Wide-band low-loss high isolation microstrip periodic-stub diplexer for multiple-frequency applications," IEEE Trans. Microw. Theory Tech., Vol. 49, No. 10, 1818-1820, 2001.
doi:10.1109/22.954789 Google Scholar

12. Wang, R., J. Xu, M.-Y. Wang, and Y.-L. Dong, "Synthesis of microwave resonator diplexers using linear frequency transformation and optimization," Progress In Electromagnetics Research, Vol. 124, 441-455, 2012.
doi:10.2528/PIER12011108 Google Scholar

13. 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. Microw. Theory Tech., Vol. 54, No. 5, May 2006. Google Scholar

14. An, J., G.-M. Wang, C.-X. Zhang, and P. Zhang, "Diplexer using composite right-/left-handed transmission line," Electronics Letters, Vol. 44, No. 11, May 22, 2008. Google Scholar

15. Yang, R.-Y., C.-M. Hsiung, C.-Y. Hung, and C.-C. Lin, "Design of a high band isolation diplexer for GPS and WLAN system using modified stepped-impedance resonators," Progress In Electromagnetics Research, Vol. 107, 101-114, 2010.
doi:10.2528/PIER10060913 Google Scholar

16. Huang, C.-Y., M.-H. Weng, and C.-S. Ye, "A high band isolation and wide stopband diplexer using dual-mode stepped-impedance resonators," Progress In Electromagnetics Research, Vol. 100, 299-308, 2010.
doi:10.2528/PIER09112701 Google Scholar

17. 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. Google Scholar

18. Wong, S. W., K.Wang, Z.-N. Chen, and Q.-X. Chu, "Rotationally symmetric coupled-lines bandpass filter with two transmission zeros," Progress In Electromagnetics Research, Vol. 135, 641-656, 2013. Google Scholar

19. Gomez-Garcia, R. and J. I. Alonso, "Design of sharp-rejection and low-loss wide-band planar filters using signal-interference techniques," IEEE Microwave Wireless Compon. Lett., Vol. 15, No. 8, 530-532, Aug. 2005.
doi:10.1109/LMWC.2005.852797 Google Scholar

20. Zysman, G. I. and A. K. Johnson, "Coupled transmission line networks in an inhomogeneous dielectric medium," IEEE Trans. Microw. Theory Tech., Vol. 17, No. 10, 753-759, Oct. 1969.
doi:10.1109/TMTT.1969.1127055 Google Scholar

21. Schwindt, R. and C. Nguyen, "Spectral domain analysis of three symmetric coupled lines and application to a new bandpass filter," IEEE Trans. Microw. Theory Tech., Vol. 42, No. 7, 1183-1189, Jul. 1994.
doi:10.1109/22.299755 Google Scholar

22. Tripathi, V. K., "On the analysis of symmetrical three-line microstrip circuits," IEEE Trans. Microw. Theory Tech., Vol. 25, No. 9, 726-729, Sept. 1977.
doi:10.1109/TMTT.1977.1129202 Google Scholar

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

Prof. Sai Wai Wong

Dr. Xiao-Han Liu

Dr. Kai Wang

Dr. Ruisen Chen

Dr. Li-Sheng Zheng

Prof. Qing-Xin Chu