A compact microstrip ultra-wideband (UWB) bandpass filter (BPF) including a narrow notched band within the UWB passband is proposed. The proposed filter is constructed by combination of two highly compact wideband bandpass filters (BPFs) with different physical dimensions which are designed on the basis of a folded-T-shaped stepped impedance resonator (SIR) and parallel-coupling feed structure. The wideband BPFs can be designed separately, and the design procedure is described. The narrow notched band with 3.8% 3 dB fractional bandwidth (FBW) from 5.15 to 5.35 GHz (IEEE 802.11a lower band) is created in order to eliminate interference from wireless local area network (WLAN) with the determined UWB passband. The center frequency and bandwidth of the notched band can be controlled by tuning the structural parameters. The full-wave EM simulated and measured results are in good agreement, showing that the proposed filter possesses good characteristics including wide passband, high selectivity, low insertion loss, large notch deep and sharp rejection.
2. Deng, H.-W., Y.-J. Zhao, X.-S. Zhang, L. Zhang, and S.-P. Gao, "Compact quintuple-mode UWB bandpass filter with good out-of-band rejection," Progress In Electromagnetics Research Letters, Vol. 14, 111-117, 2010.
doi:10.2528/PIERL10030912
3. Li, R. and L. Zhu, "Compact UWB bandpass filters using stub-loaded multiple-mode resonator," IEEE Microw. Wireless Compon. Lett., Vol. 17, No. 1, 40-42, Jan. 2007.
doi:10.1109/LMWC.2006.887251
4. Huang, J.-Q. and Q.-X. Chu, "Compact UWB band-pass filter utilizing modified Composite right/left-handed structure with cross coupling," Progress In Electromagnetics Research, Vol. 107, 179-186, 2010.
doi:10.2528/PIER10070403
5. Chou, T.-C., M.-H. Tsai, and C.-Y. Chen, "A low insertion loss and high selectivity UWB bandpass filter using composite right/left-handed material," Progress In Electromagnetics Research C, Vol. 17, 163-172, 2010.
doi:10.2528/PIERC10100501
6. Wang, J.-K., Y.-J. Zhao, L. Qiang, and Q. Sun, "A miniaturized UWB BPF based on novel scrlh transmission line structure," Progress In Electromagnetics Research Letters, Vol. 19, 67-73, 2010.
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.
doi:10.2528/PIERL08020902
8. Shobeyri, M. and M. H. Vadjed-Samiei, "Compact ultra-wideband bandpass filter with defected ground structure," Progress In Electromagnetics Research Letters, Vol. 4, 25-31, 2008.
doi:10.2528/PIERL08050205
9. An, J., G.-M. Wang, W. D. Zeng, and L.-X. Ma, "UWB filter using defected ground structure of Von Koch fractal shape slot," Progress In Electromagnetics Research Letters, Vol. 6, 61-66, 2009.
doi:10.2528/PIERL08121309
10. 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.
doi:10.2528/PIER07082302
11. Qiang, L., Y.-J. Zhao, Q. Sun, W. Zhao, and B. Liu, "A compact UWB Hmsiw bandpass filter based on complementary split-ring resonators," Progress In Electromagnetics Research C, Vol. 11, 237-243, 2009.
doi:10.2528/PIERC09112102
12. Mondal, P. and Y. L. Guan, "A coplanar stripline ultra-wideband bandpass filter with notch band," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 1, 22-24, Jan. 2010.
doi:10.1109/LMWC.2009.2035956
13. Pirani, S., J. Nourinia, and C. Ghobadi, "Band-notched UWB BPF design using parasitic coupled line," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 8, 444-446, Aug. 2010.
doi:10.1109/LMWC.2010.2049830
14. Hsu, C.-Y., H.-R. Chuang, and C.-Y. Chen, "Compact microstrip UWB dual-band bandpass filter with tunable rejection band," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 5-6, 617-626, 2009.
doi:10.1163/156939309788019741
15. Yang, G.-M., R. Jin, C. Vittoria, V.-G. Harris, and N.-X. Sun, "Small ultra-wideband (UWB) bandpass filter with notched band," IEEE Microw. Wireless Compon. Lett., Vol. 8, No. 3, 176-178, Mar. 2008.
doi:10.1109/LMWC.2008.916781
16. Hsiao, P.-Y. and R.-M. Weng, "Compact open-loop UWB filter with notched band," Progress In Electromagnetics Research Letters, Vol. 7, 149-159, 2009.
doi:10.2528/PIERL09022501
17. Jiang, T., C.-Y. Liu, Y.-S. Li, and M.-Y. Zhu, Reasearch on a novel microstrip UWB notch-band BPF, Proc. Asia-Pacific Microw. Conf. (APMC), 261-264, Dec. 2009.
18. Mondal, P. and Y. L. Guan, Ultra-wideband (UWB) bandpass filters: Full passband and with notch-band implemented, Proc. International Conference on Microwave and Millimeter Wave Technology (ICMMT), 1-4, Jan. 2007.
19. Hsiao, P.-Y. and R.-M. Weng, "Compact tri-layer ultra-wideband band-pass filter with dual notch bands," Progress In Electromagnetics Research, Vol. 106, 49-60, 2010.
doi:10.2528/PIER10040204
20. Hao, Z.-C. and J.-S. Hong, "Compact UWB filter with double notch-bands using multilayer LCP technology," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 8, 500-502, Aug. 2009.
doi:10.1109/LMWC.2009.2024828
21. Shaman, H. and J.-S. Hong, "Ultra-wideband (UWB) bandpass filter with embedded band notch structures," IEEE Microw. Wireless Compon. Lett., Vol. 17, No. 3, 193-195, Mar. 2007.
doi:10.1109/LMWC.2006.890467
22. Kuo, J.-T., S.-C. Tang, and S.-H. Lin, "Quasi-elliptic function bandpass filter with upper stopband extension and high rejection level using cross-coupled stepped-impedance resonators," Progress In Electromagnetics Research, Vol. 114, 395-405, 2011.
23. Namsang, A. and P. Akkaraekthalin, "Microstrip bandpass filters usig end-coupled asymmetrical step-impedance resonators for wide-spurios response ," Progress In Electromagnetics Research C, Vol. 14, 53-65, 2010.
doi:10.2528/PIERC10012704
24. Chin, K.-S. and D.-J. Chen, "Novel microstrip bandpass filters using direct-coupled triangular stepped-impedance resonators for spurios suppression ," Progress In Electromagnetics Research Letters, Vol. 12, 11-20, 2009.
doi:10.2528/PIERL09090602
25. Chang, Y.-C., C.-H. Kao, and M.-H.Weng, "A compact wideband bandpass filter using single asymmetric SIR with low loss and high selectivity," Microwave and Opt. Tech. Lett., Vol. 51, No. 1, 242-244, Jan. 2008.
doi:10.1002/mop.24023
26. Chang, Y.-C., C.-H. Kao, M.-H. Weng, and R.-Y. Yang, "Design of the compact wideband bandpass filter with low loss, high selectivity and wide stopband," IEEE Microw. Wireless Compon. Lett., Vol. 18, No. 12, 770-772, Dec. 2008.
doi:10.1109/LMWC.2008.2007691
27. Sagava, M., M. Makimoto, and S. Yamashita, "Geometrical structures and fundamental characteristics of microwave stepped-impedance resonators," IEEE Trans. Microw. Theroy Tech., Vol. 45, No. 7, 1078-1085, Jul. 1997.
doi:10.1109/22.598444
28. Makimoto, M. and S. Yamashita, Microwave Resonators and Filters for Wireless Communication: Theory, Design, and Application, Springer, New York, 2000.