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International Journal of Antennas and Propagation
Volume 2012, Article ID 721565, 7 pages
http://dx.doi.org/10.1155/2012/721565
Research Article

Harmonic Suppressed Slot Antennas Using Rectangular/Circular Defected Ground Structures

Wave Propagation and Microwave Measurement Research Laboratory, Department of Electrical Engineering, Amirkabir University of Technology, Tehran 15914, Iran

Received 19 October 2011; Accepted 20 May 2012

Academic Editor: Dalia N. Elshiekh

Copyright © 2012 Mohammad Saeid Ghaffarian 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

Two wide rectangle-shaped microstrip-fed 2.6-GHz slot antennas using defected ground structures (DGSs) with a low design complexity are proposed to achieve wideband harmonic suppression. To accomplish this, two rectangular DGSs (RDGSs) in the first antenna and two circular DGSs (CDGSs) in the second one with various dimensions are etched into the ground plane, which could have a wideband-stop characteristic. Simulated and measured reflection coefficients indicate that the two proposed structures effectively suppress the second and third harmonics up to 23 dB between 3.5 and 10.5 GHz with a maximum ripple of 2.4 dB. In addition, the radiation patterns and peak gains of the antennas can be suppressed at least 17 dB and 7.1 dBi, respectively, at the third harmonic frequency of 7.86 GHz.