A new approach to design a microstrip ultra-wideband (UWB) bandpass filter (BPF) with quad sharply notched bands and good selectivity is proposed using quad parallel defected microstrip structures (PDMSs). The initial UWB BPF comprises interdigital coupled lines and an E-shaped multiple-mode resonator (EMMR) to achieve two transmission zeros on both sides of the passband thus to improve skirt selectivity. Then, four PDMSs are introduced, which have the properties of achieving four band-notched characteristics and provide high degree of adjusting freedom. To validate the design theory, a new microstrip UWB BPF with four notched bands respectively centered at 5.3, 5.9, 6.4, and 7.4 GHz is designed and fabricated. Both simulation and experimental results are provided with good agreement. The designed methodology is very efficient and useful for filter synthesis though the design principle is simple.
2. Assaf, M., A. Malki, and A. A. Sarhan, "Synthesis and design of MMR-based ultrawideband (UWB) band pass filter (BPF) in suspended stripline (SSL) technology," Progress In Electromagnetics Research Letters, Vol. 84, 123-130, 2019.
doi:10.2528/PIERL19031602
3. Comez-Garcia, R. and J. I. Alonso, "Systematic method for the exact synthesis of ultra-wideband filtering responses using high-pass and low-pass sections," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 10, 3751-3764, 2006.
doi:10.1109/TMTT.2006.882883
4. Liu, B. W., Y. Z. Yin, Y. Yang, S. H. Jing, and A. F. Sun, "Compact UWB bandpass filter with two notched bands based on electromagnetic bandgap structures," Electron. Lett., Vol. 47, No. 13, 757-758, 2011.
doi:10.1049/el.2011.1281
5. Mokhtarani, A. and A. Ahmadi, "A compact UWB band pass filter using simple defected ground structures," Progress In Electromagnetics Research Letters, Vol. 79, 17-24, 2018.
doi:10.2528/PIERL17112001
6. Shaman, H. and J. S. Hong, "Asymmetric parallel-coupled lines for notch implementation in UWB filter," IEEE Microw. Wirel. Compon. Lett., Vol. 17, No. 7, 516-518, 2007.
doi:10.1109/LMWC.2007.899314
7. Song, K. and Q. Xue, "Compact ultra-wideband (UWB) bandpass filters with multiple notched bands," IEEE Microw. Wirel. Compon. Lett., Vol. 20, No. 8, 447-449, 2010.
doi:10.1109/LMWC.2010.2050303
8. Wei, F., Q. Y. Wu, X. W. Shi, and L. Chen, "Compact UWB BPF with triple-notched bands based on stub loaded resonator," Electron. Lett., Vol. 49, No. 2, 124-126, 2013.
doi:10.1049/el.2012.2885
9. Tang, C. and N. Yang, "Design of compact microstrip UWB bandpass filter with triple-notched bands," Progress In Electromagnetics Research Letters, Vol. 58, 9-16, 2016.
doi:10.2528/PIERL15072904
10. Wang, J., J. Zhao, and J. L. Li, "Compact UWB bandpass filter with triple notched bands using parallel U-shaped defected microstrip structure," Electronics Letters, Vol. 50, No. 2, 89-91, 2014.
doi:10.1049/el.2013.3077