This letter proposes a novel ultra-wideband (UWB) bandpass filter with compact size and high-selectivity performance. The filter has been studied and implemented through multiple-mode resonator (MMR) using new coupling schemes such as capacitive source-load (S-L) coupling/inductive source-load (S-L) coupling. By properly adjusting the length and width of these stubs, its first four resonant modes can be allocated within the 3.1-10.6 GHz passband, whereas its fifth resonant mode is placed above 16.0 GHz. Two transmission zeros (an inherent transmission zero and an additional transmission zero) can be produced. Moreover, the position of the additional zero can be controlled by adjusting the direct coupling inductance/capacitance. Simulated and measured results are in good agreement indicating that the proposed BPF has a passband (3.0-11.0 GHz)/(2.92-10.6 GHz) and a wide stopband width with 23 dB/25 dB attenuation up to 27.0 GHz. The group delay of the filter is relatively constant and less than 0.65 ns/0.52 ns over the operating pass band.
2. Saito, A., H. Harada, and A. Nishikata, "Development of band pass filter for ultra wideband (UWB) communication," Proc. IEEE Conf. Ultra Wideband Systems Technology, 76-80, 2003.
3. Ishida, H. and K. Araki, "Design and analysis of UWB bandpass filter with ring filter," IEEE MTT-S Int. Dig., 1307-1310, Jun. 2004.
4. Zhu, L., S. Sun, and W. Menzel, "Ultra-wideband (UWB) bandpass filters using multiple-mode resonator," IEEE Microw. Wireless Compon. Lett., Vol. 15, No. 11, 796-798, Nov. 2005.
5. Wei, F., P. Chen, L. Chen, and X. W. Shi, "Design of a compact UWB bandpass filter with wide defected ground structure," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 13, 1783-1790, 2008.
6. Fallahzadeh, S. and M. Tayarani, "A new microstrip UWB bandpass filter using defected microstrip structure," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 7, 893-902, 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.
8. Lee, C.-H., I-C. Wang, and L.-Y. Chen, "MMR-based band-notched UWB bandpass filter design," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 17–18, 2407-2415, 2008.
9. Zhao, J., J. Wang, and J.-L. Li, "Compact microstrip UWB bandpass filter with triple-notched band," Progress In Electromagnetics Research C, Vol. 44, 13-26, 2013.
10. Wong, S. W. and L. Zhu, "EBG-embedded multiple-mode resonator for UWB bandpass filter with improved upper-stopband performance," IEEE Microw. Wireless Compon. Lett., Vol. 17, No. 6, 421-423, Jun. 2007.
11. Peng, H., J. Zhao, and B. Wang, "Compact microstrip UWB bandpass filter with triple-notched bands and wide upper stopband," Progress In Electromagnetics Research, Vol. 144, 185-191, 2014.
12. Yao, B. Y., Y. G. Zhou, and Q. S. Cao, "Compact UWB bandpass filter with improved upper-stopband performance," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 6, 27-29, Jun. 2009.