The proposed filter satisfies the Federal Communications Commission ultra-wideband (FCC-UWB) specifications, and also creates and controls sharp rejection notch-bands within the filter's passband in order to provide interference immunity from unwanted radio signals, such as wireless local area networks (WLAN) and worldwide interoperability for microwave access (WIMAX) that cohabit within the UWB spectrum. This filter is based on CRLH concept consisting of an asymmetric transmission line unit cell with a short circuited inductive stub to realize high performance in an operation band from 3.1 to 10.6 GHz with a very compact size of 16.4mm × 5.0 mm. The main advantage of the proposed filter is that four notch frequencies are tuned in the UWB frequency band. The notch frequencies of the filter can be changed by increasing the length of the coupling stub which is controlled by using switching matrix equipment (Mini Circuit) instead of PIN diodes. To validate the design theory, a microstrip UWB BPF with four notch bands centered at frequencies 6.18, 5.9, 5.7, and 5.5GHz is designed and fabricated.
2. Hsu, C. L., F. C. Hsu, and J. T. Kuo, "Microstrip bandpass filters for Ultra-Wideband (UWB) wireless communications," IEEE MTT-S International Microwave Symposium Digest, 679-682, 2005.
doi:10.1002/mop.21133
3. Hong, J. S. and H. Shaman, "An optimum ultra-wide-band microstrip filter," Microwave and Optical Technology Letters, Vol. 47, 230-233, 2005.
doi:10.1109/LMWC.2013.2287231
4. Li, X. and X. Ji, "Novel compact UWB bandpass filters design with cross-coupling between short-circuited stubs," IEEE Microwave and Wireless Components Letters, Vol. 24, 23-25, 2014.
doi:10.1109/LMWC.2005.859011
5. Zhu, L., S. Sun, and W. Menzel, "Ultra-wideband (UWB) bandpass filters using multiple-mode resonator," IEEE Microwave and Wireless Components Letters, Vol. 15, 796-798, 2005.
doi:10.1109/LMWC.2012.2201930
6. Xu, J., W. Wu, W. Kang, and C. Miao, "Compact UWB bandpass filter with a notched band using radial stub loaded resonator," IEEE Microwave and Wireless Components Letters, Vol. 22, No. 7, 351-353, July 2012.
doi:10.1109/LMWC.2006.890467
7. Shaman, H. and J. S. Hong, "Ultra-wideband (UWB) bandpass filter with embedded band notch structure," IEEE Microwave and Wireless Components Letters, Vol. 17, No. 3, 193-195, March 2007.
doi:10.1109/LMWC.2011.2109942
8. Kim, C. H. and K. Chang, "Ultra wideband (UWB) ring resonator bandpass filter with a notched band," IEEE Microwave and Wireless Components Letters, Vol. 21, No. 4, 206-208, April 2011.
doi:10.1109/TMTT.2015.2405066
9. Garcia, R. G. and A. C. Guyette, "Reconfigurable multi-band microwave filters," IEEE Transactions on Microwave Theory and Techniques, Vol. 63, No. 4, 1294-1307, April 2015.
doi:10.1109/TMTT.2013.2296530
10. Wang, H., K. W. Tam, S. K. Ho, W. Kang, and W. Wu, "Design of ultra-wideband bandpass filters with fixed and reconfigurable notch bands using terminated cross-shaped resonators," IEEE Transactions on Microwave Theory and Techniques, Vol. 62, No. 2, 252-265, February 2014.
doi:10.1109/TAP.2016.2585183
11. Horestani, A. K., Z. Shaterian, J. Naqui, F. Martin, and C. Fumeaux, "Reconfigurable and tunable S-shaped split-ring resonators and application in band-notched UWB antennas," IEEE Transactions on Antennas and Propagation, Vol. 64, No. 9, 3766-3776, September 2016.
doi:10.1109/ICMMT.2016.7761773
12. Liang, J. G., X. Zhang, and L. Sun, "Compact UWB bandpass filter with triple notched bands using quadruple-mode resonator," IEEE International Conference on Microwave and Millimeter Wave Technology (ICMMT), Vol. 1, 354-356, Beijing, China, June 2016.
13. Zheng, X., W. Liu, X. Zhang, and T. Jiang, "Design of dual band-notch UWB bandpass filter based on T-shaped resonator," Progress In Electromagnetic Research Symposium, 4482-4486, Shanghai, China, August 8-11, 2016.
doi:10.1109/TMTT.2012.2231432
14. Ahmed, K. U. and B. Virdee, "Ultra-wide band bandpass filter based on composite right/left handed transmission-line unit cell," IEEE Transactions on Microwave Theory and Techniques, Vol. 61, No. 2, 782-788, February 2013.
doi:10.1049/el.2012.2885
15. Wei, F., Z. D. Wang, F. Yang, and X. W. Shi, "Compact UWB BPF with triple-notched bands based on stub loaded resonator," IEEE Electronics Letters, Vol. 49, No. 2, 124-126, January 2013.
doi:10.1109/LMWC.2013.2296291
16. Song, Y., G. M. Yang, and G. Wen, "Compact UWB bandpass filter with dual notched bands using defected ground structures," IEEE Microwave and Wireless Components Letters, Vol. 24, No. 4, 230-232, April 2014.
doi:10.1109/LMWC.2013.2262928
17. Zhu, H. and Q. X. Chu, "Ultra-wideband bandpass filter with a notch-band using stub-loaded ring resonator," IEEE Microwave and Wireless Components Letters, Vol. 23, No. 7, 341-343, July 2013.
18. Shan, Q., C. Chen, and W. Wu, "Design of an UWB bandpass filter with a notched band using asymmetric loading stubs," IEEE International Conference on Microwave and Millimeter Wave Technology (ICMMT), Vol. 2, 5-8, June 2016.