volume | PIER Journals

Abstract

The frequency response characteristics of a basic microstrip lowpass filter improved using H-shaped defected ground structures are presented. The proposed defected ground structures behave as a resonant element at high frequency and thus eliminate the stopband frequencies to achieve wide stopband rejection. The 3 dB cutoff frequency of the filter is 1.935 GHz. Due to the defects etched in the ground plane of the basic structure, the harmonic rejection is improved from 5th to 10th order along with low insertion loss and voltage standing wave ratio together with good selectivity. The compact filter has a size of 0.0338λ_g², with λ_g = 85.18 mm being the guided wavelength at cutoff frequency. The characteristics of the lowpass filter are verified through simulation and measurement. Consistent and stable results are obtained.

1. Pozar, D. M., Microwave Engineering, 2nd Ed., Wiley, New York, 1998.

2. Hong, J. S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, Wiley, New York, 2001.
doi:10.1002/0471221619

3. Hsieh, L.-H. and K. Chang, "Compact elliptic-function low-pass filters using microstrip stepped-impedance Hairpin resonators,", Vol. 51, No. 1, 193-199, 2003.

4. Rekha, T. K., P. Abdulla, P. M. Raphika, and P. M. Jasmine, "Compact microstrip lowpass filter with ultra-wide stopband using patch resonators and open stubs," Progress In Electromagnes Research C, Vol. 72, 15-28, 2017.
doi:10.2528/PIERC16110202

5. Velidi, V. K. and S. Sanyal, "Sharp roll-off lowpass filter with wide stopband using stub-loaded coupled line Hairpin unit," IEEE Microwave Wireless Compon. Lett., Vol. 21, No. 6, 301-303, 2011.
doi:10.1109/LMWC.2011.2132120

6. Ahn, D., J.-S. Park, C.-S. Kim, J. Kim, Y. Qian, and T. Itoh, "A design of the low-pass filter using the novel microstrip defected ground structure," IEEE Trans. Microwave Theory Tech., Vol. 49, No. 1, 86-93, 2001.
doi:10.1109/22.899965

7. Park, J.-S., J.-H. Kim, J.-H. Lee, S.-H. Kim, and S.-H. Myung, "A novel equivalent circuit and modeling method for defected ground structure and its application to optimization of a DGS lowpass filter," IEEE MTT-S International Microwave Symposium Digest, Vol. 1, 417-420, 2002.

8. Abdel-Rahman, A., A. K. Verma, A. Boutejdar, and A. S. Omar, "Control of bandstop response of Hi-Lo microstrip low-pass filter using slot in ground plane," IEEE Trans. Microwave Theory Tech., Vol. 52, No. 31008-1013, 2004.

9. Weng, L. H., Y.-C. Guo, X.-W. Shi, and X.-Q. Chen, "An overview on defected ground structure," Progress In Electromagnetics Research B, Vol. 7, 173-189, 2008.
doi:10.2528/PIERB08031401

10. Kurgan, P. and M. Kitlinski, "Novel microstrip low-pass filters with fractal defected ground structures," Microwave Opt. Technol. Lett., Vol. 51, No. 10, 2473-2477, 2009.
doi:10.1002/mop.24607

11. Boutejdar, A. and W. A. Ellatif, "Improvement of compactness of low pass filters using new quasi-Yagi-DGS-resonator and multilayer-technique," Progress In Electromagnetics Research C, Vol. 69, 115-124, 2016.
doi:10.2528/PIERC16073003

12. Xi, D., Y.-Z. Yin, L.-H. Wen, Y. Mo, and Y. Wang, "A compact low-pass filter with sharp cutoff and low insertion loss characteristic using novel defected ground structure," Progress In Electromagnetics Research Letters, Vol. 17, 133-143, 2010.
doi:10.2528/PIERL10062501

13. Xiao, M., G. Sun, and X. Li, "A lowpass filter with compact size and sharp roll-off," IEEE Microwave Wireless Compon. Lett., Vol. 25, No. 12, 790-792, 2015.
doi:10.1109/LMWC.2015.2496801

14. Zhang, P. and M. Li, "A novel sharp roll-off microstrip lowpass filter with improved stopband and compact size using dual-plane structure," Microwave Opt. Technol. Lett., Vol. 58, No. 5, 1085-1088, 2016.
doi:10.1002/mop.29753

15. Belbachir, A. K., M. Boussouis, and N. Amar Touhami, "High-performance LPF using coupled C-shape DGS and radial stub resonator for microwave mixer," Progress In Electromagnetics Research Letters, Vol. 58, 97-103, 2016.
doi:10.2528/PIERL15090105

16. Wang, C. J. and T. H. Lin, "A multi-band meandered slotted-ground plane resonator and its application of lowpass filter," Progress In Electromagnetics Research, Vol. 120, 249-262, 2011.
doi:10.2528/PIER11072203

Dr. Thulaseedharan Rekha

Dr. Parambil Abdulla

Dr. Puthenveetil Muhammed Jasmine

Dr. Paruthikkal Mohammed Raphika