1. Pozar, D. M., Microwave Engineering, 3rd Ed., Wiley, New York, 2005.
2. Bonache, J., et al., "Application of composite right/left handed (CRLH) transmission lines based on complementary split ring resonators (CSRRs) to the design of dual-band microwave components," IEEE Microw. Wireless Compon. Lett., Vol. 18, No. 8, 524-526, 2008.
doi:10.1109/LMWC.2008.2001011
3. Zhang, Y., L. Hu, and S.-L. He, "A tunable dual-broad-band branch-line coupler utilizing composite right/left-handed transmission lines," Journal of Zhejiang University Science, Vol. 6A, No. 6, 483-486, 2005.
doi:10.1631/jzus.2005.A0483
4. Chi, P.-L. and T. Itoh, "Miniaturized dual-band directional couplers using composite right/left-handed transmission structures and their applications," IEEE Trans. Microw. Theory Tech., Vol. 57, No. 5, 1207-1215, 2009.
doi:10.1109/TMTT.2009.2017350
5. Chen, W.-L. and G.-M. Wang, "Design of novel miniaturized fractal-shaped branch-line couplers," Microwave Opt. Technol. Lett., Vol. 50, No. 5, 1198-1201, 2008.
doi:10.1002/mop.23316
6. Ghali, H. and T. A. Moselhy, "Miniaturized fractal ratrace,branch-line and coupled-line hybrids," IEEE Trans. Microw. Theory Tech., Vol. 52, No. 11, 2513-2520, 2004.
doi:10.1109/TMTT.2004.837154
7. Sun, K.-O., S.-J. Ho, C.-C. Yen, and D. van der Weide, "A compact branch-line coupler using discontinuous microstrip lines," IEEE Microw. Wireless Compon. Lett., Vol. 15, No. 8, 519-520, 2005.
doi:10.1109/LMWC.2005.852789
8. Tang, C.-W., M.-G. Chen, and C.-H. Tsai, "Miniaturization of microstrip branch-line coupler with dual transmission lines," IEEE Microw. Wireless Compon. Lett., Vol. 18, No. 3, 185-187, 2008.
doi:10.1109/LMWC.2008.916798
6. Li, B., X. Wu, and W. Wu, "A Miniaturized branch-line coupler with wideband harmonics suppression," Progress In Electromagnetics Research Letters, Vol. 17, 181-189, 2010.
doi:10.2528/PIERL10082602
10. Crnojevic-Bengin, V., V. Radonic, and B. Jokanovic, "Fractal geometries of complementary split-ring resonators," IEEE Trans. Microw. Theory Tech., Vol. 56, No. 10, 2312-2321, 2008.
doi:10.1109/TMTT.2008.2003522
11. Xu, H.-X., G.-M. Wang, C.-X. Zhang, and Y. Hu, "Microstrip approach benefits quad splitter," Microwaves & RF, Vol. 49, No. 6, 92-96, 2010.
12. Falconer, K., Fractal Geometry, J. Wiley & Sons, New York, 2003.
13. Xu, H.-X., G.-M. Wang, C.-X. Zhang, and K. Lu, "Novel design of composite right/left handed transmission line based on fractal shaped geometry of complementary split ring resonators," Journal of Engineering Design, Vol. 18, No. 1, 71-76, 2011.
14. Smith, D. R., S. Schultz, P. Markos, and C. M. Soukoulis, "Determination of effective permittivity and permeability of metamaterials from reflection and transmission coefficients," Phys. Rev. B, Vol. 65, 195104, 2002.
doi:10.1103/PhysRevB.65.195104
15. Itoh, T., Planar Transmission Line Structures, IEEE Press, New York, 1987.
16. Chen, X., et al., "Robust method to retrieve the constitutive effective parameters of metamaterials," Phys. Rev. E, Vol. 70, 016608, 2004.
doi:10.1103/PhysRevE.70.016608
17. Wang, W.-X., Microwave Engineering, Ch. 5, 128-129, China National Defense Industry Press, Beijing, 2009.
18. Bahl, I., Lumped Elements for RF and Microwave Circuits, Ch. 14, 462-465, Artech House, Boston, 2003.