volume | PIER Journals

Abstract

Defected ground structures (DGSs) are often utilized in planar filters and antennas for compactness and spurious frequency suppressions by creating defects or slots on the ground planes. One disadvantage of conventional DGS filters is that the overall dimension increases as the order of the filter increases. In this research, we proposed an asymmetric finger-shape DGS which created multiple equivalent LC resonators when combining with a capacitive microstrip gap on the top. In contrast to the conventional high-order DGS filter by generating many DGSs on the ground plane, the finger-shape DGS provided a high-order bandpass response with one single DGS due to the capacitances between the top metallic strip and the ground plane. Therefore, we developed a wide-band, high-order, and spurious frequency suppressed microstrip bandpass filter with a compact size. To achieve these features, different filter design techniques were exploited including stepped impedance resonator (SIR), series-coupled resonator, and nger-shape DGSs. The main advantage of our DGS filter was that it had a higher-order and wider bandpass responses than other harmonic-suppressed work. A prototype was designed, fabricated, and measured with a calibrated vector network analyzer (VNA) where the simulations matched with the measurements. The finger-shape DGS filter demonstrated a passband centered at 2.35 GHz with a fractional bandwidth of 72.3%, the spurious frequency suppression up to 8.5f₀ where f₀ was the center frequency of the passband, and a compact size of 0.034λ₀² where λ₀ was the wavelength corresponding to f₀.

1. Barth, C., I. R. Linscott, and U. S. Inan, "An image frequency rejection filter for SAW-less GPS receivers," IEEE Transactions on Circuits and Systems I: Regular Papers, Vol. 59, No. 5, 1085-1092, 2012.
doi:10.1109/TCSI.2012.2188933 Google Scholar

2. Chaudhary, G., Y. Jeong, and J. Lim, "Harmonic suppressed dual-band bandpass filters with tunable passbands," IEEE Transactions on Microwave Theory and Techniques, Vol. 60, No. 7, 2115-2123, 2012.
doi:10.1109/TMTT.2012.2197020 Google Scholar

3. Zhang, X. Y., Q. Xue, C. H. Chan, and B. J. Hu, "Low-loss frequency-agile bandpass filters with controllable bandwidth and suppressed second harmonic," IEEE Transactions on Microwave Theory and Techniques, Vol. 58, No. 6, 1557-1564, 2010.
doi:10.1109/TMTT.2010.2048250 Google Scholar

4. Tu, W.-H. and K. Chang, "Compact second harmonic-suppressed bandstop and bandpass filters using open stubs," IEEE Transactions on Microwave Theory and Techniques, Vol. 54, No. 6, 2497-2502, 2006.
doi:10.1109/TMTT.2006.875802 Google Scholar

5. Chaudhary, G., Y. Jeong, and J. Lim, "Dual-band bandpass filter with independently tunable center frequencies and bandwidths," IEEE Transactions on Microwave Theory and Techniques, Vol. 61, No. 1, 107-116, 2013.
doi:10.1109/TMTT.2012.2222910 Google Scholar

6. Huynh, C. and C. Nguyen, "New technique for synthesizing concurrent dual-band impedancematching filtering networks and 0.18 μm SiGe BiCMOS 25.5/37-GHz concurrent dual-band power amplifier," IEEE Transactions on Microwave Theory and Techniques, Vol. 61, No. 11, 3927-3939, 2013.
doi:10.1109/TMTT.2013.2281035 Google Scholar

7. Kuo, J. T. and E. Shih, "Microstrip stepped impedance resonator bandpass filter with an extended optimal rejection bandwidth," IEEE Transactions on Microwave Theory and Techniques, Vol. 51, No. 5, 1554-1559, 2003.
doi:10.1109/TMTT.2003.810138 Google Scholar

8. Lin, S.-C., P.-H. Deng, Y.-S. Lin, C.-H. Wang, and C. H. Chen, "Wide-stopband microstrip bandpass filters using dissimilar quarter-wavelength stepped-impedance resonators," IEEE Transactions on Microwave Theory and Techniques, Vol. 54, No. 3, 1011-1018, 2006.
doi:10.1109/TMTT.2005.864139 Google Scholar

9. Kuo, J.-T., T.-H. Yeh, and C.-C. Yeh, "Design of microstrip bandpass filters with a dual-passband response," IEEE Transactions on Microwave Theory and Techniques, Vol. 53, No. 4, 1331-1337, 2005.
doi:10.1109/TMTT.2005.845765 Google Scholar

10. Aziz, M. A., A. M. E. Safwat, F. Podevin, and A. Vilcot, "Coplanar waveguide filters based on multibehavior etched-ground stubs," IEEE Transactions on Components and Packaging Technologies, Vol. 32, No. 4, 816-824, 2009.
doi:10.1109/TCAPT.2009.2030418 Google Scholar

11. Barakat, A., R. Pokharel, and T. Kaho, "60 GHz on-chip mixed coupled BPF with H-shaped defected ground structures," Electronics Letters, Vol. 52, No. 7, 533-535, 2016.
doi:10.1049/el.2015.4465 Google Scholar

12. Chen, H. J., T. H. Huang, C. S. Chang, L. S. Chen, J. H. Horng, Y. H. Wang, and M. P. Houng, "A compact bandpass filter with enhanced stopband characteristics by an asymmetric crossshape defected ground structure," IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 53, No. 11, 2183-2187, 2006.
doi:10.1109/TUFFC.2006.158 Google Scholar

13. Abdel-Rahman, A., A. K. Verma, A. Boutejdar, and A. S. Omar, "Compact stub type microstrip bandpass filter using defected ground plane," IEEE Microwave and Wireless Components Letters, Vol. 14, No. 4, 136-138, 2004.
doi:10.1109/LMWC.2003.821503 Google Scholar

14. Park, J.-S., J.-S. Yun, and D. Ahn, "A design of the novel coupled-line bandpass filter using defected ground structure with wide stopband performance," IEEE Transactions on Microwave Theory and Techniques, Vol. 50, No. 9, 2037-2043, 2002.
doi:10.1109/TMTT.2002.802313 Google Scholar

15. Karshenas, F., A. R. Mallahzadeh, and J. Rashed-Mohassel, "Size reduction and harmonic suppression of parallel coupled-line bandpass filters using defected ground structure," 2009 13th International Symposium on Antenna Technology and Applied Electromagnetics and the Canadian Radio Science Meeting, 1-6, 2009. Google Scholar

16. Luo, X., J. G. Ma, E. P. Li, and K. Ma, "Hybrid microstrip T-stub/defected ground structure cell for electromagnetic interference bandpass filter design," IEEE Transactions on Electromagnetic Compatibility, Vol. 53, No. 3, 717-725, 2011.
doi:10.1109/TEMC.2011.2114667 Google Scholar

17. Luo, X. and J. G. Ma, "Compact slot-line bandpass filter using backside microstrip open-stubs and air- bridge structure for spurious suppression," 2009 Asia Pacific Microwave Conference, 882-885, 2009.
doi:10.1109/APMC.2009.5384302 Google Scholar

18. Luo, X., H. Qian, J. G. Ma, and K. S. Yeo, "A compact wide stopband microstrip bandpass filter using quarter-wavelength shorted coupled-lines," 2010 Asia-Pacific Microwave Conference, 1142-1145, 2010. Google Scholar

19. Chen, J. X., Y. L. Li, W. Qin, Y. J. Yang, and Z. H. Bao, "Compact multi-layer bandpass filter with wide stopband using selective feeding scheme," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 65, No. 8, 1009-1013, 2017.
doi:10.1109/TCSII.2017.2782692 Google Scholar

20. Kumar, A. and G. Bharti, "Spurious response suppression using triple grooves in PCML bandpass filter," 2017 International Conference on Innovations in Information, Embedded and Communication Systems (ICIIECS), 1-3, 2017. Google Scholar

21. Pal, B. and S. Dwari, "A compact parallel coupled wideband bandpass filter with DGS and spurline," 2015 International Conference on Microwave and Photonics (ICMAP), 1-2, 2015. Google Scholar

22. Hayati, M., H. A. Memari, and H. Abbasi, "Compact microstrip lowpass filter with sharp roll-off and wide stopband using semicircle ended stub resonator," Progress In Electromagnetics Research Letters, Vol. 35, 73-81, 2012.
doi:10.2528/PIERL12082110 Google Scholar

Dr. Yih-Dar Chen

Prof. Chien-Hao Liu