Miniature Slotted Semi-Circular Dual-Band Antenna for WiMAX and WLAN Applications

In this paper, a new approach is presented for designing a miniaturized microstrip patch antenna (MPA) for dual-band applications. The proposed MPA consists of a semi-circular patch radiator fed by a 50-Omega coplanar waveguide (CPW) structure with a tapered-ground plane for enhancing impedance bandwidth over the dual-band. By inserting a folded U-shaped slot into the semi-circular patch, the proposed antenna introduces an additional higher-order mode but does not modify the resonance frequency of the lower-order mode of the patch, yielding the desired dual-band response. For antenna miniaturization, the circular-shaped radiator of the reference antenna (RA) was converted into a semi-circular radiating patch. Agreement between CST and HFSS simulated results led us to manufacture a prototype of the designed antenna on one side of an inexpensive FR-4 substrate with an overall dimension of 17 x 18 x 0.8 mm(3). The measured result in terms of reflection coefficient S11 confirms that the antenna operates in both 3.5 GHz (3.4-3.7 GHz) and 5.8 GHz (5.725-5.875 GHz) bands suitable for use in WiMAX and WLAN applications, respectively. Moreover, besides an area reduction of 32% compared with the RA counterpart, the proposed antenna has other features, a simple geometry, and is easy to manufacture in comparison with previously reported antenna structures.