In this paper several Defected Microstrip Structure (DMS) are used to suppress the first and second spurious responses in microstrip hairpin filters. The DMSs are integrated in filter structure, and therefore this method keeps the filter size unchanged. The DMS interconnection disturbs the current distribution only across the strip, thereby giving a modified microstrip line with certain stop band. The undesired spurious harmonics are suppressed through multiple transmission zeros which are added at these frequencies by designed DMSs. Experimental results verify that 25 dB suppression for the first harmonic and 40 dB suppression for the second harmonic, respectively, without affecting the main passband response. There is a good agreement between the simulated and measured results.
2. Pozar, D. M., Microwave Engineering, 2 Ed., Wiley, New York, 1998.
3. Hong, J. S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, Wiley, New York, 2001.
doi:10.1002/0471221619
4. Afkhami, A. and M. Tayarani, "Spurious response suppression in hairpin filter using CSRR merged in the filter structure," Progress In Electromagnetics Research C, Vol. 11, 137-146, 2009.
doi:10.2528/PIERC09102001
5. Velazquez-Ahumada, M. C., J. Martel, and F. Medina, "Parallel coupled microstrip filters with ground-plane aperture for spurious band suppression and enhanced coupling," IEEE Trans. Microw. Theory Tech., Vol. 52, No. 3, 1082-1086, 2004.
doi:10.1109/TMTT.2004.823593
6. Wang, S. M., C. H. Chi, M. Y. Hsieh, and C. Y. Chang, "Miniaturized spurious passband suppression microstrip filter using meandered parallel coupled lines," IEEE Trans. Microw. Theory Tech., Vol. 53, No. 2, 747-753, 2005.
doi:10.1109/TMTT.2004.840619
7. Bonache, J., I. Gil, J. García-García, and F. Martín, "Novel microstrip bandpass filters based on complementary split-ring resonators," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 1, 265-271, 2006.
doi:10.1109/TMTT.2005.861664
8. Moradian, M. and M. Tayarani, "Spurious-response suppression in microstrip parallel-coupled bandpass filters by grooved substrates," IEEE Trans. Microw. Theory Tech., Vol. 56, No. 7, 1707-1713, 2008.
doi:10.1109/TMTT.2008.925239
9. 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 Trans. Microw. Theory Tech., Vol. 49, No. 9, 1593-1598, 2001.
doi:10.1109/22.942571
10. Kuo, J. T., W. H. Hsu, and W. T. Huang, "Parallel coupled microstrip filters with suppression of harmonic response," IEEE Microw. Wireless Compon. Lett., Vol. 12, No. 10, 383-385, 2002.
doi:10.1109/LMWC.2002.804559
11. Kim, B. S., J. W. Lee, and M. S. Song, "An implementation of harmonic-suppression microstrip filters with periodic grooves," IEEE Microw. Wireless Compon. Lett., Vol. 14, No. 9, 413-415, 2004.
doi:10.1109/LMWC.2004.832063
12. 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 Trans. Microw. Theory Tech., Vol. 53, No. 9, 2943-2948, 2005.
doi:10.1109/TMTT.2005.854263
13. Kazerooni, M., A. Cheldavi, and M. Kamarei, "Unit length parameters, transition sharpness and level of radiation in defected microstrip structure (DMS) and defected ground structure (DGS) interconnections," Progress In Electromagnetics Research M, Vol. 10, 93-102, 2009.
doi:10.2528/PIERM09101907
Submit
