Multi band circularly polarized asymmetrical fractal boundary microstrip patch antenna using DGS for (2.58/3.02/5.58/6.44GHZ)

Abstract

A design of compact multi band circularly polarized asymmetrical fractal boundary microstrip patch antenna with DGS (defected ground structure) and fractal boundary techniques has been proposed. Using the DGS technique a cross slot and circle are cut away at the centre of the ground plane to enhance the single band to multi band. The structure is asymmetrical along to the principal axes (x, y) because the radius of fractals are different and probe feed is applied at the diagonal of square patch then the excellent CP(circular polarization) is achieved. In the both techniques the proposed antenna sizes also reduce, besides the gain and directivity increase. Experimental results show as 10 dB return loss, gain and circular polarization at the frequencies 2.58, 3.02, 5.58, and 6.44 GHz. More over the 50 ohms feed position is optimized by moving the feed point along the diagonal of the square patch and get the effective gain and directivity grater then 6 dB at each frequency. The overall dimension of the proposed antenna is 42×42×3.3 mm3. This proposed antenna is used for Wi- MAX and WLAN applications.