Vol. 40

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Miniaturized Hybrid Branch Line Couplers Based on a Square-Split Resonator Loading Technique

By Lamia Al-Khateeb
Progress In Electromagnetics Research Letters, Vol. 40, 153-162, 2013


In this paper, new miniaturized hybrid branch line couplers loaded by square-split ring resonators are proposed. This loading technique increases the electrical length of transmission lines by patterning the ground plane under the conductor trace in microstrip lines with the complementary, dual-behavior, configuration of square-split ring resonators. Each branch is loaded by one resonator in the first coupler and by two resonators in the second coupler. Hence, compact sizes of 9.29 mm × 9.57 mm, and 8.88 mm × 9.11 mm, or equivalently 0.2λg × 0.2λg and 0.19λg × 0.19λg, respectively, are obtained at the operation frequency, 2.4 GHz. This corresponds to 66.14% and 60.18% of a conventional structure's area, respectively. Moreover, the new designs can suppress higher harmonic components due to the bandstop response of the square-split resonators at their resonant frequency while maintaining similar measured performance compared to the conventional branch-line hybrid coupler. Measured and simulated responses are in very good agreement which validates the proposed structures and technique. This technique can also be applied to minimize the size of other microwave circuits.


Lamia Al-Khateeb, "Miniaturized Hybrid Branch Line Couplers Based on a Square-Split Resonator Loading Technique," Progress In Electromagnetics Research Letters, Vol. 40, 153-162, 2013.


    1. Pendry, J. B., A. J. Holden, D. J. Ribbins, and W. J. Stewart, "Magnetism from conductors and enhanced nonlinear phenomena," IEEE Trans. Microwave Theory Tech., Vol. 47, 2075-2084, Nov. 1999.

    2. Baena, J. D., J. Bonache, F. Martin, R. Marques, F. Falcone, T. Lopetegi, M. A. G. Laso, J. Garcia, I. Gil, and M. Sorolla, "Equivalent-circuit models for split-ring resonators and complementary split-ring resonators coupled to planar transmission lines," IEEE Trans. Microwave Theory Tech., Vol. 53, No. 4, 1451-1461, Apr. 2005.

    3. Caloz, C., H. Okabe, H. Iwai, and T. Itoh, "Transmission line approach of left-handed metamaterials," USNC/URSI National Science Meeting, San Antonio, TX, Jun. 16-21, 2002.

    4. Saha, C., J. Y. Siddiqui, and Y. M. M. Antar, "Square split ring resonator backed coplanar waveguide for filter applications," 2011 XXXth URSI General Assembly and Scientific Symposium, 1-4, Aug. 13-20, 2011.

    5. Falcone, F., T. Lopetegi, J. D. Baena, R. Marques, F. Martin, and M. Sorolla, "Effective negative-ε stopband microstrip lines based on complementary split ring resonators," IEEE Microw. Wireless Compon. Lett., Vol. 14, No. 6, 280-282, Jun. 2004.

    6. Pasakawee, S. and Z. Hu, "Left-handed microstrip delay line implemented by complementary split ring resonators (CSRRs)," Asia Pacific Microwave Conference 2009, 599-601, 2009.

    7. Eccleston, K. W. and S. H. M. Ong, "Compact planar microstripline branch-line and rat-race couplers," IEEE Trans. Microwave Theory Tech., Vol. 51, No. 10, 2119-2125, Oct. 2003.

    8. Shum, K. M., Q. Xue, and C. H. Chan, "A novel microstrip ring hybrid incorporating a PBG cell," IEEE Microw. Wireless Compon. Lett., Vol. 11, No. 6, 258-260, Jun. 2001.

    9. Mondal, P. and A. Chakrabarty, "Design of miniaturised branch-line and rat-race hybrid couplers with harmonics suppression," IET Microwaves, Antennas & Propagation, Vol. 3, No. 1, 109-116, Feb. 2009.

    10. Bekasiewicz, A., P. Kurgan, and M. Kitlinski, "New approach to a fast and accurate design of microwave circuits with complex topologies," topologies," IET Microwaves, Antennas & Propagation, Vol. 6, No. 14, 1616-1622, Nov. 2012.

    11. Jung, S.-C., R. Negra, and F. M. Ghannouchi, "A design methodology for miniaturized 3-dB branch-line hybrid couplers using distributed capacitors printed in the inner area," IEEE Trans. Microwave Theory Tech., Vol. 56, No. 2, 2950-2953, 2008.

    12. Marques, R., F. Mesa, J. Martel, and F. Medina, "Comparative analysis of edge- and broadside-coupled split ring resonators for metamaterial design --- Theory and experiment," IEEE Trans. Antennas Propag., Vol. 51, No. 10, 2572-2581, Oct. 2003.

    13. Zhang, J. and X.-W. Sun, "Harmonic suppression of branch-line and rat-race coupler using complementary spilt ring resonators (CSRR) cell," Progress In Electromagnetics Research Letters, Vol. 2, 73-79, 2008.

    14. Zeland Software, Inc., "IE3D simulator,", Fremont, CA, 2007.

    15. Simons, R. N., Coplanar Waveguide Circuits, Components, and Systems, John Wiley & Sons, New York, 2001.

    16. Martin, F., F. Falcone, J. Bonache, R. Marques, and M. Sorolla, "A new split ring resonator based left handed coplanar waveguide," Appl. Phys. Lett., Vol. 83, 4652-4654, 2003.