A novel UWB bandpass filter (BPF) based on the composite right/left-handed (CRLH) material and 0° feeding structure is proposed. With multiple unit-cells cascaded, the new section comprises the series interdigital capacitors and the shunt short-circuited stub inductors in the symmetric configuration. The circuit is designed to be unbalanced, a tunable gap between left handed and right handed modes in the β-ω diagram can control out of band performance. With careful design, a bandpass filter with wide rejection band can be achieved. Furthermore, by using the 0° feeding associated structure, two extra transmission zeros are created just outside the intended passband. Finally, a three cells bandpass filter has been designed and fabricated with 1.1 dB insertion loss at the center frequency of 4.2 GHz. Two transmission zeros are located at 2.95 GHz and 6.18 GHz with attenuations of -44.1 dB and -37.3 dB, respectively. Also, a wide rejection band from 5.4 to 9 GHz is obtained.
2. Simovski, C. R., P. A. Belov, and H. Sailing, "Backward wave region and negative material parameters of a structure formed by lattices of wires and split-ring resonators," IEEE Trans. Antennas Propagat., Vol. 51, 2582-2591, Oct. 2003.
3. Ziolkowski, R. W. and A. D. Kipple, "Application of double negative materials to increase the power radiated by electrically small antennas," IEEE Trans. Antennas Propagat., Vol. 51, 2626-2640, Oct. 2003.
4. Kim, H., A. B. Kozyrev, A. Karbassi, and D. W. Van derWeide, "Linear tunable phase shifter using a left-handed transmission line," IEEE Microw. Wireless Compon. Lett., Vol. 15, No. 5, 366-368, May 2005.
5. Mao, S.-G., M.-S.Wu, Y.-Z. Chueh, and C. H. Chen, "Modeling of symmetric composite right/left-handed coplanar waveguides with applications to compact bandpass filters," IEEE Trans. Microw. Theory Tech., Vol. 53, No. 11, 3460-3466, Nov. 2005.
6. Zhu, L., V. K. Devabhaktuni, and C. Wang, "CAD of left-handed transmission line bandpass filters," PIERS Online, Vol. 3, No. 1, 77-82, 2007.
7. Li, C., K. Y. Liu, and F. Li, "Analysis of composite right/left-handed coplanar waveguide zeroth-order resonators with application to a band-pass filter," PIERS Online, Vol. 3, No. 5, 599-602, 2007.
8. Hirota, A., Y. Tahara, and N. Yoneda, "A compact forward coupler using coupled composite right/left-handed transmission lines," IEEE Trans. Microw. Theory Tech., Vol. 57, No. 12, 3127-3133, Dec. 2009.
9. Sanada, A., C. Caloz, and T. Itoh, "Characteristics of the composite right/left-handed transmission lines," IEEE Microw. Wireless Compon. Lett., Vol. 14, No. 2, 68-70, Feb. 2004.
10. Tsai, C.-M., S.-Y. Lee, and C.-C. Tsai, "Performance of a planar filter using a zero-degree feed structure," IEEE Trans. Microwave Theory and Tech., 2362-2367, Oct. 2002.
11. Lim, S., S., C. Caloz, and T. Itoh, "Metamaterial-based electronically controlled transmission line structure as a novel leaky-wave antenna with tunable radiation angle and beamwidth," IEEE Trans. Microwave Theory Tech., Vol. 53, No. 1, 161-173, Jan. 2005.
12. Caloz, C., A. Sanada, and T. Itoh, "A novel composite right-/left-handed coupled-line directional coupler with arbitrary coupling level and broad bandwidth," IEEE Trans. Microw. Theory Tech., Vol. 52, No. 3, 980-992, Mar. 2004.