Table of Contents
International Journal of Microwave Science and Technology
Volume 2010 (2010), Article ID 671515, 9 pages
http://dx.doi.org/10.1155/2010/671515
Research Article

New Design Method of UWB Microstrip Filters Using Adaptive Genetic Algorithms with Defected Ground Structures

1Faculty of Electrical Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz, Iran
2Faculty of Electrical Engineering, Shahed University, Tehran 3319118651, Iran

Received 9 August 2009; Revised 5 January 2010; Accepted 6 March 2010

Academic Editor: Safieddin Safavi-Naeini

Copyright © 2010 Amir Reza Dastkhosh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The effects of adaptive genetic algorithms (AGAs) and defected ground structures (DGSs) on performance optimization of tapered microstrip filter are investigated. The proposed structure achieves an ultra wide stopband with high attenuation within a small surface area, as well as 45% smaller size, in comparison with conventional filters. The parameters of the filter are optimized using in-home AGA code. In the proposed AGA algorithm, the crossover and mutation probabilities are adaptively changed according to the value of individual fitness. Then by utilizing the proposed DGS, a compact S-band lowpass filter with ultra-wide spurious free window is obtained. The proposed filter achieves an insertion loss of 0.8 dB from DC up to 4 GHz and 21 dB rejection in the stopband from 4.3 up to 60 GHz. The fabricated and measured results exhibit good agreement with the simulated results. They demonstrate that combining AGA and DGS yields best possible response for this group of filters.