A single-side-access ring resonator topology is presented. It employs a single quarter-wavelength coupled-line that couples to a one-wavelength ring to exhibit a single-mode resonance with transmission zeros. A global synthesis is presented, in order to control the transmission zeros in its response. As the transmission zeros of the ring resonator maintains their positions when multiple identical rings are used, the global synthesis can further be used for the design of higher order filters with multiple rings. Furthermore, since only one coupled-line is used in the resonator topology, only one section of line is present in the ring, other than the coupled-line. Hence, there will be no second section of the ring that needs to be adjusted to obtain the symmetrical response during its realization, as compared to other types of ring topologies. To show the advantage of the synthesis, it is applied in the design of higher order ring-based bandpass filters, which also involve extra quarter-wavelength coupled-lines to create additional poles. Five bandpass ring filters up to 5th-order were realized using microstrip technology, and measured to validate the proposed concept. Measurement results showing good agreement with those from the simulation are also presented throughout the paper.
2. Luo, S. and L. Zhu, "A dual-mode dual-band bandpass filter using a single slot ring resonator," Progress In Electromagnetics Research Letters, Vol. 23, 173-180, 2011.
3. Chiou, Y. C. and P. S. Yang, "Transmission zero design graph for dual-mode dual-band filter with periodic stepped-impedance ring resonator," Progress In Electromagnetics Research, Vol. 108, 23-36, 2010.
doi:10.2528/PIER10071608
4. Keshvari, M. and M. Tayarani, "A novel miniaturised bandpass filter based on complimentary split ring resonators (CSRRs) and open-loop resonators," Progress In Electromagnetics Research Letters, Vol. 23, 165-172, 2011.
5. Zhou, L., S. Liu, H. Zhang, X. Kong, and Y. Guo, "Compact dual-band bandpass ¯lter using improved split ring resonators based on stepped impedance resontor," Progress In Electromagnetics Research Letters, Vol. 23, 57-63, 2011.
6. Liu, Y., X. Tang, Z. Zhang, and X. Huang, "Novel nested split-ring-resonator (SRR) for compact filter application," Progress In Electromagnetics Research, Vol. 136, 765-773, 2013.
7. Zhang, L., Z. Y. Yu, and S. G. Mo, "Novel planar multimode bandpass filters with radial-line stubs," Progress In Electromagnetics Research, Vol. 101, 33-42, 2010.
doi:10.2528/PIER09121303
8. Prabhu, S. and J. S. Mandeep, "Microstrip bandpass filter at S band using capacitive coupled resonator," Progress In Electromagnetics Research, Vol. 76, 223-228, 2007.
doi:10.2528/PIER07071205
9. Mohd Salleh, M. K., G. Prigent, O. Pigaglio, and R. Crampagne, "Quarter-wavelength side-coupled ring resonator for bandpass filters," IEEE Transactions on Microwave Theory and Techniques, Vol. 56, 156-162, Jan. 2008.
doi:10.1109/TMTT.2007.912167
10. Ma, Z., H. Sasaki, C. Chun-Ping, T. Anada, and Y. Kobayashi, "Design of a wideband bandpass filter using microstrip parallel-coupled dual-mode ring resonator," 2010 Asia-Pacific Microwave Conference Proceedings (APMC), 21-24, 2010.
11. Ozaki, H. and J. Ishii, "Synthesis of a class of strip-line filters," IRE Trans. on Circuit Theory, Vol. 5, No. 2, 104-109, Jun. 1568.
12. Sato, R. and E. G. Cristal, "Simplified analysis of coupled transmission-line networks and their application (short paper)," IEEE Transactions on Microwave Theory and Techniques, Vol. 18, 122-131, 1970.
doi:10.1109/TMTT.1970.1127172
13. Nemoto, Y., K. Kobayashi, and R. Sato, "Graph transformations of nonuniform coupled transmission line networks and their application," IEEE Transactions on Microwave Theory and Techniques, Vol. 33, No. 11, 1257-1263, Nov. 1985.
doi:10.1109/TMTT.1985.1133208
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