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2017-11-05

A Semi-Elliptical Wideband Directional Coupler

By Yew-Chiong Lo, Boon-Kuan Chung, and Eng Hock Lim
Progress In Electromagnetics Research C, Vol. 79, 139-148, 2017
doi:10.2528/PIERC17082205

Abstract

A new design of wideband directional couplers using a semi-elliptical edge-coupled structure is presented. This structure consists of two semi-elliptical patches on the top layer and an elliptical defected ground plane on the bottom layer to increase the coupling coefficient and operating bandwidth. Even and odd mode analysis is performed, and sets of design graphs are formulated to facilitate the design of the coupler on substrate with dielectric constants of 2.2 and 3.38. The operating frequency and coupling are controlled by the dimensions of the elliptical patch and the size of the air gap. Compared to the conventional parallel-microstrip coupler which requires extremely narrow air gap to achieve tighter coupling factor, the semi-elliptical coupler allows for wider air gap to be used, and it reduces fabrication difficulty. Both simulation and measurement results show that the proposed design exhibits wideband characteristic with a bandwidth ratio of more than 2.4 with acoupling deviation of ±1 dB.

Citation


Yew-Chiong Lo, Boon-Kuan Chung, and Eng Hock Lim, "A Semi-Elliptical Wideband Directional Coupler," Progress In Electromagnetics Research C, Vol. 79, 139-148, 2017.
doi:10.2528/PIERC17082205
http://jpier.org/PIERC/pier.php?paper=17082205

References


    1. Pozar, D. M., Microwave Engineering, 4th Ed., John Wiley & Sons, 2011.

    2. Wu, Y., W. Sun, S.-W. Leung, Y. Diao, K.-H. Chan, and Y.-M. Siu, "Single-layer microstrip highdirectivity coupled-line coupler with tight coupling," IEEE Trans. Microw. Theory Techn., Vol. 61, No. 2, 746-753, Feb. 2013.
    doi:10.1109/TMTT.2012.2235855

    3. Tang, "Design of wide passband microstrip branch-line couplers with multiple sections," IEEE Trans. Compon., Packag., Manuf. Technol., Vol. 4, No. 7, 1222-1227, Jul. 2014.
    doi:10.1109/TCPMT.2014.2320499

    4. Lange, J., "Interdigitated strip-line quadrature hybrid," IEEE Trans. Microw. Theory Techn., Vol. 17, No. 12, 1150-1151, Dec. 1969.
    doi:10.1109/TMTT.1969.1127115

    5. Ou, W. P., "Design equations for an interdigitated directional coupler," IEEE Trans. Microw. Theory Techn., Vol. 23, No. 2, 253-255, Feb. 1975.
    doi:10.1109/TMTT.1975.1128534

    6. Kajfez, D., Z. Paunovic, and S. Pavlin, "Simplified design of Lange coupler," IEEE Trans. Microw. Theory Techn., Vol. 26, No. 10, 806-808, Oct. 1978.
    doi:10.1109/TMTT.1978.1129490

    7. Han, L., K. Wu, and X. P. Chen, "Accurate synthesis of four-line interdigitated coupler," IEEE Trans. Microw. Theory Techn., Vol. 57, No. 10, 2444-2455, Oct. 2009.

    8. Kemp, G., J. Hobdell, and J. W. Biggin, "Ultra-wideband quadrature coupler," Electron. Lett., Vol. 19, No. 6, 197-199, Mar. 1983.
    doi:10.1049/el:19830137

    9. Cho, J. H., H. Y. Hwang, and S. W. Yun, "A design of wideband 3-dB coupler with N-section microstrip tandem structure," IEEE Microw. Wireless Compon. Lett., Vol. 15, No. 2, 113-115, Feb. 2005.
    doi:10.1109/LMWC.2004.842850

    10. Tang, C. W., C. T. Tseng, and K. C. Hsu, "Design of the modified planar tandem couplers with a wide passband," IEEE Trans. Microw. Theory Techn., Vol. 61, No. 1, 48-54, Jan. 2013.
    doi:10.1109/TMTT.2012.2226745

    11. Tanaka, T., K. Kusoda, and M. Aikawa, "Slot-coupled directional couplers between double-sided substrate microstrip lines and their applications," IEEE Trans. Microw. Theory Techn., Vol. 36, No. 12, 1752-1757, Dec. 1988.
    doi:10.1109/22.17410

    12. Abbosh, A. M. and M. E. Bialkowski, "Design of compact directional couplers for UWB applications," IEEE Trans. Microw. Theory Techn., Vol. 55, No. 2, 189-194, Feb. 2007.
    doi:10.1109/TMTT.2006.889150

    13. Chang, C. P., J. C. Chiu, H. Y. Chiu, and Y. H.Wang, "A 3-dB quadrature coupler using broadsidecoupled coplanar waveguides," IEEE Microw. Wireless Compon. Lett., Vol. 18, No. 3, 191-193, Mar. 2008.
    doi:10.1109/LMWC.2008.916805

    14. Weng, L. H., Y. C. Guo, X. W. Shi, and X. Q. Chen, "An overview on defected ground structure," Progress In Electromagnetics Research B, Vol. 7, 173-189, 2008.
    doi:10.2528/PIERB08031401

    15. Del Castillo Velazquez-Ahumada, M., J. Martel, and F. Madina, "Parallel coupled microstrip filters with ground plane aperture for spurious band suppression and enhanced coupling," IEEE Trans. Microw. Theory Tech., Vol. 52, No. 3, 1082-1086, Mar. 2004.
    doi:10.1109/TMTT.2004.823593

    16. Wang, S. and L. Song, "Design and simulation of a kind of wide band microwave coupler with defected ground structure," IEEE International Conference on Electronic Information and Communication Technology, 462-465, 2016.

    17. Lo, Y. C. and B. K. Chung, "A semi-elliptical wideband phase shifter," Progress In Electromagnetic Research Letters, Vol. 28, 91-99, 2012.
    doi:10.2528/PIERL11102303