A new compact microstrip ultra-wideband (UWB) bandpass filter (BPF) with improved out-of-band rejection and good selectivity is proposed using a modified ring multiple-mode resonator (MMR). The initial UWB bandpass filter comprises interdigital coupled lines and a conventional ring MMR. Then, four high-low impedance resonant cells are periodically placed in the inner area of the conventional ring MMR, which have the properties of achieving harmonic suppression and size reduction. To validate the design theory, a new compact microstrip UWB BPF with improved out-of-band rejection is designed and fabricated. Both simulated and experimental results are provided with good agreement.
2. Naghshvarian-Jahromi, M., "Novel wideband planar fractal monopole antenna," IEEE Trans. Antennas Propag., Vol. 56, No. 12, 3844-3849, 2008.
3. Naser-Moghadasi, M., H. Rousta, and B. S. Virdee, "Compact UWB planar monopole antenna," IEEE Antennas Wirel. Propag. Lett., Vol. 8, 1382-1385, 2009.
4. Mazinani, S. M. and H. R. Hassani, "A novel broadband plate-loaded planar monopole antenna," IEEE Antennas Wirel. Propag. Lett., Vol. 8, 1123-1126, 2009.
5. Sun, M., Y. P. Zhang, and Y. Lu, "Miniaturization of planar monopole antenna for ultra-wideband radios," IEEE Trans. Antennas Propag., Vol. 58, No. 7, 2420-242, 2010.
6. Lee, W.-S., D.-Z. Kim, K.-J. Kim, and J.-W. Yu, "Wideband planar monopole antennas with dual band-notched characteristics," IEEE Trans. Microwave Theory Tech., Vol. 54, 2800-2806, 2006.
7. Chung, K., J. Kim, and J. Choi, "Wideband microstrip-fed monopole antenna having frequency band-notch function," IEEE Microwave Wireless Compon. Lett., Vol. 15, 766-768, 2005.
8. Kim, Y. and D. H. Kwon, "CPW-fed planar ultra wideband antenna having a frequency band notch functions," Electron. Lett., Vol. 40, 403-405, 2004.
9. Yin, K. and J. P. Xu, "Compact ultra-wideband antenna with dual bandstop characteristic," Electron. Lett., Vol. 44, 453-454, 2008.
10. Bi, D.-H., Z.-Y. Yu, S.-G. Mo, and X.-C. Yin, "Two new ultra-wideband antennas with 3.4/5.5GHz dual band-notched characteristics," Microwave Opt. Tech. Nol. Lett., Vol. 51, 2942-2945, 2009.
11. Lin, X. Q., R. P. Liu, and X. M. Yang, "Arbitrary dual-band components using simplified structures of conventional CRLH TLs," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 7, 2902-2909, Jul. 2006.