A new double arrow head defected ground structure (DGS) with centered etched ellipse is proposed for designing a multilayer low pass filter (LPF) with wide rejection band and low insertion loss in the stop-band. The prototype LPF consists of three double arrow head DGS with centered etched ellipse in the ground plane and compensated capacitor on the top layer of a 30×40 mm2 Roger RT/Duroid5880 substrate having relative permittivity (εr) of 2.2 and thickness of 0.78 mm. The cutoff frequency is equal to 1.07 GHz .The prototype LPF is then realized as multilayer structure to enhance the filter response and reduce its size. The size reduction of the proposed multi-layer LPF is about 26% more than the conventional one. The proposed filter has been fabricated and measured. Good agreement is achieved between the simulated and measured results. The filter presents the advantages of compact size; low insertion loss and high out-band suppression. Finally, the multilayer LPF is transformed to band pass filter (BPF) using J-inverter method.
2. Lim, J. S., C. S. Kim, T. Y. Lee, D. Ahn, and Nam, "Design of low pass filters using defected ground structure and compensated microstrip line," Electronic Letters, Vol. 38, 1357-1358, 2002.
3. Boutejdar, A. and A. S. Omar, "A miniature 5.2-GHz band stop microstrip filter using multilayer technique and coupled octagonal defected ground structure," Microwave and Optical Technology Letters, Vol. 51, 2810-2813, 2009.
4. Ahn, D., J. Park, C. 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, 86-93, 2001.
5. Rahman, A., A. Boutejdar, A. K. Verma, G. Nadim, and A. S. Omar, "Improved circle model for DGS based lowpass filter," IEEE Antennas and Propagation Symposium, Vol. 1, 998-1001, 2004.
6., , http://www.ansoft.com/products/hf/hfss/.
7. Awida, M., A. Boutejdar, A. Safwat, H. El-Hennawy, and A. Omar, "Multi-bandpass filters using multi-armed open loop resonators with direct feed," IEEE MTT-S International Microwave Symposium, Honolulu, Hawaii, June 2007.
8. Li, M., L. Haiwen, A. Boutejdar, W. Shuxin, and F. Tong, "Novel microstrip bandpass filter with slotted hexagonal resonators and capacitive loading," Proc. 38th EUMC , Amsterdam, The Netherlands, October 2008.
9. Al Sharkawy, M. H., A. Boutejdar, F. Alhefnawi, and O. Luxor, "Improvement of compactness of lowpass/bandpass filter using a new electromagnetic coupled crescent defected ground structure resonators," Applied Computational Electromagnetics Society (ACES) Journal, Vol. 25, No. 7, 2010.