This paper presents a design and optimization approach for a tri-band miniature planar rectangular patch antenna structure for wireless mobile applications. The tri-band operation while maintaining a compact size has been achieved by introducing a defected ground structure (DGS) to control the surface current distribution on the patch antenna and consequently achieve multi-band operation. The geometry of the patch and the position of the DGS were optimized by a genetic algorithm to achieve the desired performance using a simple and miniature design with an area of 16 mm × 20 mm × 1.6 mm, an 82% reduction in the area occupied by a conventional single-band structure used in the optimization process. The proposed GA-optimised antenna provided tri-band operation with bandwidths for |?11| > 6 from 3.2 - 3.5 GHz, 5.5 - 5.9 GHz and 6.3 - 7.1 GHz. At the centre frequencies of 3.4, 5.7 and 6.7 GHz, the peak gains were 0.7, 1.76 and 2.93 dB, respectively. The optimally designed antenna is etched on an FR-4 substrate. Simulation and measurement results show good agreement, making the proposed structure a suitable candidate for mobile applications requiring small and multifunctional telecommunication devices.
Key words: Defected ground structure, genetic algorithm, tri-band, miniaturization, wireless mobile applications
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