A Compact Single Feed, Low Cost Broadband Switched-beam Antenna for Mobile Wimax Applications

A broadband and low cost switched beam antenna suitable for WIMAX applica- tions is presented in this paper. Present mobile terminal antennas are expected to show increased bandwidth as well as low-loss impedance matching while maintaining low-proflle geometry. A custom Genetic Algorithm (GA) is used in order to optimize the proposed array's parameters regarding resonation frequency and radiation pattern. The optimized antenna exhibits small size (dimensions 12 £ 12cm), satisfactory directivity for mobile terminal applications of 6.2 dB over an operation bandwidth of 120MHz around the central frequency of 3.5GHz. Simulation results and parameters range are exposed below followed by the according radiation pattern and variation of the simulated VSWR. With the rapid growth of wireless mobile communication technology and the demand for broadband applications the world is looking a new, potentially disruptive, technology. The mobile WIMAX technology is an ideal mean for a new generation of mobile web applications that are being supple- mented by a simultaneous shift in consumer behavior. The major change in the consumer behavior can be summarized as a strong move towards mobility. In that case more and more attention is being paid to the design of new handsets ofiering wider bandwidth, interference cancellation, multipath fading mitigation, direction of arrival destination etc (1,2). In this paper, a Cross-PIFA array is proposed for mobile-WIMAX application in the frequency of 3.5GHz aiming to combine the Switched-Parasitic Arrays technology (SPAs) (3,4), with the wideband and low proflle Planar Inverted F Antennas (PIFAs). 2. DESIGN AND OPTIMIZATION OF THE CROSS PIFA 2.1. Architecture of the Proposed Structure The proposed structure consists of a conductive top plate (four planar inverted F antennas-PIFA's connected forming a cross) lying over a flnite sized ground plane which is interconnected through four wires (feeding wires-only one active at the time as explained later in this paper), and four other elements as shorting strips, in a conflguration designed for symmetrical coverage of the horizontal plane (Fig. 1). The radiation characteristics and performance of the array can be adjusted by altering the dimensions of the structure. Also due to the structures symmetry, by electrically controlling the active (feeding wire) and passive (shorting strips) elements, the array's beam pattern may be steered through the azimuth plane.