volume | PIER Journals

Abstract

A novel cascade microstrip filter with mixed electric and magnetic coupling is proposed and examined. For the first time, we designed a novel multilayer configuration resonator with a compact size. Compared with conventional open-loop filter, the size decreased 75%. First, using novel multilayer configuration resonator instead of monolayer configuration resonator, the size decrease about 45%. Meanwhile, two microstrip patches can be served as inner coupling capacitor, which create and strengthen electric field. Owing to this inner coupling, the size of filter can be further reduced. What's more, with a section of high characteristic impedance transmission line connected to the ground though a via-hole, it can be served as coupling inductor and create main magnetic filed, base on this structure mixed EM coupling is realized, and can generate additional transmission zero. That's means adopt low-order filter can achieve same characteristic as high-order filter. Based on the above solutions, the filter size can be sharply decreased to 12.5 mm×7.7 mm (i.e.,0.05λ_g×0.033λ_g). Furthermore, advantages of using this type filter are not only low insert loss, but also increased attenuation out-of-band with controllable transmission zeros.

1. Xiao, O. Y., "Compact quasi-elliptic filter using mixed EM coupling λ/4 stepped-impedance resonators," 2012 International Conference on Microwave and Millimeter Wave Technology (ICMMT), Vol. 4, 1-4, May 5{8, 2012.

2. Hsu, C.-Y., C.-Y. Chen, and H.-R. Chuang, "Microstrip dual-band bandpass filter design with closely specified passbands," IEEE Trans. on Microw. Theory and Tech., Vol. 61, No. 1, Jan. 2013.
doi:10.1109/TMTT.2012.2222912

3. Zhang, L., Z.-Y. Yu, and S.-G. Mo, "Novel microstrip bandpass filter with controllable transmission zeros," 2009 3rd IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications, 1016-1018, Oct. 27-29, 2009.

4. Wei, C.-L., B.-F. Jia, Z.-J. Zhu, and M.-C. Tan, "Novel trigonal dual-mode filter with controllable transmission zeros," IET Microw, Antennas Propag., Vol. 5, No. 13, 1563-1567, May 2010.
doi:10.1049/iet-map.2010.0517

5. Chu, Q.-X. and H. Wang, "A compact open-loop filter with mixed electric and magnetic coupling," IEEE Trans. on Microw. Theory and Tech., Vol. 56, No. 2, Feb. 2008.
doi:10.1109/TMTT.2007.914642

6. Wang, H. and Q.-X. Chu, "An inline coaxial quasi-elliptic filter with controllable mixed electric and magnetic coupling," IEEE Trans. on Microw. Theory and Tech., Vol. 57, No. 3, Mar. 2009.

7. Wang, H. and Q.-X. Chu, "An EM-coupled triangular open-loop filter with transmission zeros very close to passband," IEEE Microw. and Wireless Components Letters, Vol. 19, No. 2, Feb. 2009.

8. Chu, Q-X. and H. Wang, "Planar quasi-elliptic filters with inline em coupled open-loop resonators," 2008 IEEE MTT-S International Microwave Workshop Series on Art of Miniaturizing RF and Microwave Passive Components, 47-50, Chengdu, China, Dec. 2008.
doi:10.1109/IMWS.2008.4782258

9. Abdel-Rahman, A. B. and A. S. Omar, "Miniaturized bandpass filters using capacitor loaded folded slot coupled resonators," 2010-IEEE APS, Middle East Conference on Antennas and Propagation (MECAP), 1-4, Cairo, Egypt, Oct. 2010.

10. Ma, K., J.-G. Ma, K. S. Yeo, and M. A. Do, "A compact size coupling controllable filter with separate electric and magnetic coupling paths," IEEE Trans. on Microw. Theory and Tech., Vol. 54, No. 3, 1113-1119, Mar. 2006.
doi:10.1109/TMTT.2005.864118

11. Tsai, C.-M., S.-Y.Lee, and C.-C Tsai, "Performance of a planar filter using a 0^o feed structure," IEEE Trans. on Microw. Theory and Tech., Vol. 50, No. 10, 2362-2367, Oct. 2002.
doi:10.1109/TMTT.2002.803421

12. Hunter, I. C., Theory and Design of Microwave Filters, IEE Press, London, UK, 2001.
doi:10.1049/PBEW048E

13. Kuo, J.-T., C.-L. Hsu, and E. Shih, "Compact planar quasi-elliptic function filter with inline stepped-impedance resonators," IEEE Trans. on Microw. Theory and Tech., Vol. 55, No. 8, 1747-1755, Aug. 2007.
doi:10.1109/TMTT.2007.901604

14. Goldfarb, M. E. and R. A. Pucel, "Modeling via hole grounds in microstrip," IEEE Microw. Guided Wave Lett., Vol. 1, No. 6, 135-137, Jun. 1991.
doi:10.1109/75.91090

15. Hedayati, M., M. J. Kazemi, and R. Safian, "Design and implementation of a multi triangular microstrip resonator passband filter based on mixed coupling," 2011 IEEE International RF and Microwave Conference (RFM 2011), 1-4, Serernban, Malaysia, Dec. 12-14, 2011.

16. Kuo, J.-T., S.-C. Tang, and S.-H. Lin, "Quasi-elliptic 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.

17. Kuo, J.-T., T.-W. Lin, and S.-J. Chung, "New compact triple-mode resonator filter with embedded inductive and capacitive cross coupling," Progress In Electromagnetics Research, Vol. 135, 435-449, 2013.

Dr. Wei Tang

Dr. Jun He

Dr. Xiaobo Yang