In this paper, we present a novel class of microstrip bandpass filters with improved upper rejection band. The proposed filters are composed of two half-wavelength resonators and two shortended microstrip feed lines for input and output. Using voltagewave analysis, we examine the resonance and coupling properties at harmonic frequencies. It is found that different combinations of the feed line and the resonator with proper selection of the coupling regions can suppress spurious responses. Benefiting from this approach, two single-band and one dual-band bandpass filters are designed, fabricated and measured. Simulated and measured results indicate that the upper rejection bands of the proposed filters are increased up to near thirdand fifth-order harmonics, respectively. And the rejection level during the stop-bands is kept below 20 dB.
2. Chaudhary, , G., , Y. Jeong, K. Kim, and D. Ahn, "Design of dual-band bandpass fiter with controllable bandwidths using new mapping function," Progress In Electromagnetics Research,, Vol. 124, 17-34, , 2012.
doi:10.2528/PIER11111407
3. Kuo, , J.-T. , S.-W. Lai, and , "New dual-band bandpass filter with wide upper new rejection band," Progress In Electromagnetics Research, , Vol. 123, 371-384, 2012.
doi:10.2528/PIER11112304
4. Lopetegi, T., , M. A. G. Laso, J. Hernandez, M. Bacaicoa D. Benito, M. J. Garde, M. Sorolla, and M. Guglielmi, "New microstrip `wiggly-line' filters with spurious passband suppression," IEEE Microw. Theory and Tech., Vol. 49, No. 9, 1593-1598, , 2001.
doi:10.1109/22.942571
5. Kuo, , J. T., , W. H. Hsu, and W. T. Huang, "Parallel coupled microstrip ¯lters with suppression of harmonic response," IEEE Microw. Wireless Compon. Lett., Vol. 12, No. 10, 383-385, 2002.
doi:10.1109/LMWC.2002.804559
6. Kim, B. S., B. S., J. W. Lee, and M. S. Song, , "An implementation microstrip ¯lters with suppression of harmonic response," IEEE Microw. Wireless Compon. Lett., Vol. 12, No. 10, 383-385, 2002.
doi:10.1109/LMWC.2002.804559
7. Kim, I. K., , N. Kingsley, M. Morton, R. Bairavasubramanian, J. Papapolymerou, M. M. Tentzeris, and J. G. Yook, "Fractal-shaped microstrip coupled-line bandpass filters for suppression of second harmonic," IEEE Microw. Theory and Tech., Vol. 53, No. 9, 2948,-2948, 2005..
8. Wang, Y. X., , Y. X., , B.-Z. Wang, and J. P. Wang, "A compact square loop dual-mode bandpass fiter with wide stop-band," Progress In Electromagnetics Research, Vol. 77, 67-73, 2007.
doi:10.2528/PIER07072707
9. Ye, , C.-S., , Y.-K. Su, M.-H. Weng, C.-Y. Hung, and R.-Y. Yang, "Design of the compact parallel-coupled lines wideband," Progress In Electromagnetics Research,, Vol. 100, 153-173, 2010.
doi:10.2528/PIER09073002
10. Kuo, , J.-T., , C.-Y. Fan, and S.-C. Tang, , "Dual-wideband bandpass ¯lters with extended stopband based on coupled-line and coupled three-line resonators," Progress In Electromagnetics Research, Vol. 124, 1-15, 2012.
doi:10.2528/PIER11120103
11. Kuo, , J.-T. , E. Shih, and , "Microstrip stepped impedance resonator bandpass ¯lter with an extended optimal rejection bandwidth," IEEE Microw. Theory and Tech., Vol. 51, No. 5, 1554-1559, 2003.
doi:10.1109/TMTT.2003.810138
12. U-yen, K., , E. J. Wollack, T. A. Doiron, J. Papapolymerou, and J. Laskar, "A planar bandpass filter design with wide stopband using double split-end stepped-impedance resonators," IEEE Microw. Theory and Tech., Vol. 54, No. 3, 1244,-1244, 2006.
13. Zhang, , J., and Compact and, "Compact and harmonic suppression open-loop resonator bandpass with trisection SIR," Progress In Electromagnetics Research,, Vol. 69, 93-100, 2007.
doi:10.2528/PIER06120702
14. 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 Electromagnetics Research, Vol. 108, 141-153, 2010.
doi:10.2528/PIER10071802
15. Kuo, J.-T., , S.-C. Tang, and S.-H. Lin, "Quasi-electric 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.
16. Chen, C. F., T. Y. Huang, and R. B. Wu, "Design of microstrip bandpass filters with multiorder spurious-mode suppression," IEEE Microw. Theory and Tech., Vol. 53, No. 12, 3788-3793, 2005.
doi:10.1109/TMTT.2005.859869
17. Dai, , G. L., , X. Y. Zhang, C. H. Chan, Q. Xue, and M. Y. Xia, "An investigation of open- and short-ended resonators and their applications to bandpass filters," IEEE Microw. Theory and Tech.,, Vol. 57, No. 9, 2203-2210, 2209.
18. Li, , Y. C., X. Y. Zhang, and Q. Xue, , "Bandpass filter using discriminating coupling for extended out-of-band suppression," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 7, 369-371, 2010.
doi:10.1109/LMWC.2010.2049425
19. Zhang, , X. Y., Q. Xue, and , "Harmonic-suppressed bandpass fiter based on discriminating coupling," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 11, 695-697, 2009..
doi:10.1109/LMWC.2009.2032002
20. Hong, J.-S. , J.-S. , M. J. Lancaster, and , Microstrip Filters for RF/Microwave Applications,, Wiley, , New York, 2001.
doi:10.1002/0471221619
21. Chen, C. Y. , C.-Y. Hsu, and , "A simple and effective method for microstrip dual-band filters design," IEEE Microw. Wireless Compon. Lett., Vol. 16, No. 5, 246-248, 2006.
doi:10.1109/LMWC.2006.873584
22. Zhang, , X. Y. , Q. Xue, and , "Novel centrally loaded resonators and their applications to bandpass filters," IEEE Microw. Theory and Tech., Vol. 56, No. 4, 913-921, 2008..
doi:10.1109/TMTT.2008.919648
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