In this paper, a high selectivity quadruple-mode bandpass filter (BPF) with source-load coupling is proposed. This filter uses two short-circuited stubloaded stepped-impedance resonators (SIRs) which have the same type but different size. Two SIRs can generate four operating modes, which can be approximately adjusted individually. Owing to the special design of the filter, the coupling of two resonators is weak. In each resonator, the even-mode frequency can be flexibly controlled by changing the length of the short stub, whereas the odd-mode one remains stationary. Due to the source-load coupling, two transmission zeros are close to the cut-off frequencies of the passband, which leads to high selectivity. Simulated results show that central frequency is 2.27 GHz with 3-dB fractional bandwidth of 22.9%. The measured and simulated results are well complied with each other.
2. Yang, G. M., R. H. Jin, and J. P. Geng, "Planar microstrip UWB bandpass filter using U-shaped slot coupling structure," Electron. Lett., Vol. 42, No. 25, 1461-1463, 2006.
doi:10.1049/el:20062284
3. Yang, G. M., R. Jin, J. Geng, X. Huang, and G. Xiao, "Ultra-wideband bandpass filter with hybrid quasi-lumped elements and defected ground structure," IET Microw. Antennas Propag., Vol. 1, No. 3, 733-736, 2007.
doi:10.1049/iet-map:20060288
4. Adam, H., A. Ismail, M. A. Mahdi, M. S. Razalli, A. R. H. Alhawari, and B. K. Esfeh, "X-band miniaturized wideband band-pass filter utilizing multilayered microstrip hairpin resonator," Progress In Electromagnetic Research, Vol. 93, 177-188, 2009.
doi:10.2528/PIER09042202
5. Li, R. and L. Zhu, "Compact UWB bandpass filter using stub-loaded multiple-mode resonator," IEEE Microw. Wirel. Compon. Lett., Vol. 17, No. 1, 40-42, 2007.
doi:10.1109/LMWC.2006.887251
6. Han, L., K. Wu, and X.-P. Chen, "Compact ultra-wideband bandpass filter using stub-loaded resonator," Electron. Lett., Vol. 45, No. 10, 504-506, 2009.
doi:10.1049/el.2009.0510
7. Wong, S. W. and L. Zhu, "EBG-embedded multiple-mode resonator for UWB bandpass filter with improved upper-stopband performance," IEEE Microw. Wirel. Compon. Lett., Vol. 17, No. 6, 421-423, 2007.
doi:10.1109/LMWC.2007.897788
8. Wu, Y.-L., C. Liao, and X.-Z. Xiong, "A dual-wideband bandpass filter based on E-shaped microstrip sir with improved upper-stopband performance," Progress In Electromagnetic Research, Vol. 108, 141-153, 2010.
doi:10.2528/PIER10071802
9. Makimoto, M. and S. Yamashita, Microwave Resonators and Filters for Wireless Communications, Springer Series in Advanced Micro-electronics, Springer, New York, 2001.
10. Chin, K.-S., J.-L. Hung, C.-W. Huang, J. S. Fu, B.-G. Chen, and T.-J. Chen, "LTCC dual-band stepped-impedance-stub filter constructed with vertically folded," Electron. Lett., Vol. 46, No. 23, 2010.
doi:10.1049/el.2010.2347
11. Chen, C.-Y., C.-Y. Hsu, and H.-R. Chuang, "Design of miniature planar dual-band filter using dual-feeding structures and embedded resonators," IEEE Microw. Wireless Compon. Lett., Vol. 16, No. 12, 669-671, 2006.
doi:10.1109/LMWC.2006.885621
12. Singh, P. K., S. Basu, and Y.-H. Wang, "Miniature dual-band filter using quarter wavelength stepped impedance resonators," IEEE Microw. Wireless Compon. Lett., Vol. 18, No. 2, 88-90, 2008.
doi:10.1109/LMWC.2007.915032
13. Zhang, Y. P. and M. Sun, "Dual-band microstrip bandpass filter using stepped-impedance resonator with new coupling schemes," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 10, 3779-3785, 2006.
doi:10.1109/TMTT.2006.882895
14. Athukorala, L. and D. Budimir, "Compact dual-mode open loop microstrip resonators and filters," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 11, 698-670, 2009.
doi:10.1109/LMWC.2009.2032003
15. Wong, S. W. and L. Zhu, "Quadruple-mode UWB bandpass filter with improved out-of-band rejection," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 3, 152-154, 2009.
doi:10.1109/LMWC.2009.2013735
16. Yao, B. Y., Y. G. Zhou, Q. S. Cao, and Y. C. Chen, "Compact UWB bandpass filter with improved upper-stopband performance," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 1, 27-29, 2009.
doi:10.1109/LMWC.2008.2008558
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