A novel composite right/left handed transmission line is presented which is synthesized by etching Koch fractal shape slot in the ground plane and series capacitive gap in the conductor strip. Unlike the structures loaded with complementary split ring resonators (CSRRs), the proposed structure can operate at very wide band and is used to design an ultra-wideband (UWB) filter. The UWB filter is fabricated and tested. The relative bandwidth of the -10 dB return loss is 128% and the insertion loss is larger than -1.5 dB except at high frequencies. The equivalent circuit model of the proposed structure is presented and the electrical parameters are also extracted. The circuit model results are compared with the simulation and measurement results which verify that not only the extracted parameters are exact but also the equivalent circuit model is reasonable.
2. Menzel, W., M. S. R. Tito, and L. Zhu, "Low-loss ultra-wideband (UWB) filters using suspended stripline," Asia-Pacific Microwave Proceedings, 2148-2151, 2005.
3. Sun, S. and L. Zhu, "Capacitive-ended interdigital coupled lines for UWB bandpass filters with improved out-of-band performances," IEEE Microw. Wireless Compon. Lett., Vol. 16, No. 8, 440-442, Aug. 2006.
4. Hsu, C.-L., F.-C. Hsu, and J.-T. Kuo, "Microstripbandp ass filters for ultra-wideband (UWB) wireless communications," IEEE MTT-S Int. Digest, 679-682, 2005.
5. Hong, J.-S. and H. Shaman, "An optimum ultra-wideband microstrip filter," Microw. Opt. Technol. Lett., Vol. 47, No. 3, 230-233, Nov. 2005.
6. Chen, H. and Y.-X. Zhang, "A novel and compact UWB bandpass filter using microstrip fork-form resonators," Progress In Electromagnetics Research, Vol. 77, 273-280, 2007.
7. Naghshvarian-Jahromi, M. and M. Tayarani, "Miniature planar UWB bandpass filters with circular slots in ground," Progress In Electromagnetics Research Letters, Vol. 3, 87-93, 2008.
8. Falcone, F., T. Lopetegi, J. D. Baena, R. Marqués, F. Martín, and M. Sorolla, "Effective negative-ε stop-band microstrip lines based on complementary split ring resonators," IEEE Microw. Wireless Compon. Lett., Vol. 14, No. 6, 280-282, Jun. 2004.
9. Falcone, F., T. Lopetegi, M. A. G. Laso, J. D. Baena, J. Bonache, R. Marqués, F. Martín, and M. Sorolla, "Babinet principle applied to the design of metasurfaces and metamaterials," Phys. Rev. Lett., Vol. 93, 197401-4, Nov. 2004.
10. Bonache, J., M. Gil, I. Gil, J. García-García, and F. Martín, "On the electrical characteristics of complementary metamaterial resonators," IEEE Microw. Wireless Compon. Lett., Vol. 16, No. 10, 543-545, Oct. 2006.
11. Bonache, J., I. Gil, J. García-García, and F. Martín, "New microstrip filters based on complementary split rings resonators," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 1, 265-271, Jan. 2006.
12. Bonache, J., F. Martín, I. Gil, J. García-García, R. Marqués, and M. Sorolla, "Microstrip bandpass filters with wide bandwidth and compact dimensions," Microw. Opt. Technol. Lett., Vol. 46, 343-346, Aug. 2005.
13. Borja, C. and J. Romeu, "On the behavior of Koch island fractal boundary microstrip patch antenna," IEEE Trans. Antennas Propag., Vol. 51, No. 6, 1281-1291, Jun. 2003.
14. Xiao, J.-K. and Q.-X. Chu, "Novel microstrip triangular resonator bandpass filter with transmission zeros and wide bands using fractal-shaped defection," Progress In Electromagnetics Research, Vol. 77, 343-356, 2007.