Step-by-step procedures for designing a third order bandpass filter and a sixth order bandpass filter using a triple-mode resonator are described in this paper. The triple-mode resonator is a square open-loop resonator with an open circuited stepped-impedance stub and a grounding via located at the symmetrical plane of the resonator. The equations for approximating the resonant frequencies of the resonator are obtained from odd- and even-mode analysis. To design a filter, first, the theoretical resonant frequencies for the filter are calculated. Then the basic dimensions of the resonator are approximated using the equations. The filter layouts are fine-tuned by simulation and verified by experiment to conclude the paper. The first spurious response occurs at about 3 times the center frequency of the first passband in both filters. The simulated and measured results are in good agreement.
2. Chang, K. and L.-H. Hsieh, "Microwave Ring Circuits and Related Structures," Wiley, 2004.
3. Lin, S.-C. , Y.-S. Lin, and C. H. Chen, "Extended-stopband band-pass filter using both half- and quarter-wavelength resonators," IEEE Microwave and Wireless Components Letters, Vol. 16, No. 1, 43-45, Jan. 2006.
doi:10.1109/LMWC.2005.860014
4. Lin, S. C., P. H. Deng, Y. S. Li, C. H. Wang, and C. H. Chen, "Wide-stopband microstrip bandpass filters using dissimilar quarter-wavelength stepped-impedance resonators," IEEE Transactions on Microwave and Theory and Techniques, Vol. 54, No. 3, 1011-1018, Mar. 2006.
doi:10.1109/TMTT.2005.864139
5. Lee, K. C., H. T. Su, and M. K. Haldar, "Triple mode resonator bandpass filters with source-load coupling," PIERS Proceedings, 1356-1360, Suzhou, China, Sep. 12-16, 2011.
6. Tripathi, V. K., "Asymmetric coupled transmission lines in an inhomogeneous medium," IEEE Transactions on Microwave and Theory and Techniques, Vol. 23, No. 9, 734-739, Sep. 1975.
doi:10.1109/TMTT.1975.1128665
7. Kal, S., D. Bhattacharya, and N. B. Chakraborti, "Normal-mode parameters of microstrip coupled lines of unequal width," IEEE Transactions on Microwave and Theory and Techniques, Vol. 32, No. 2, 198-200, Feb. 1984.
doi:10.1109/TMTT.1984.1132645
8. Chiou, Y.-C., J.-T. Kuo, and E. Cheng, "Broadband quasi-Chebyshev bandpass filters with multimode stepped-impedance resonators (SIRs)," IEEE Transactions on Microwave and Theory and Techniques, Vol. 54, No. 8, 3352-3358, Aug. 2006.
doi:10.1109/TMTT.2006.879131
9. Sonnet User's Manuals: Release 13-Version 13.54. Sonnet Software Inc. , North Syracuse, , NY, 2011.
Submit
