Wedge-shaped dual planar log-periodic antenna with enhanced directivity for WiMAX applications

A dual planar log-periodic antenna with a significantly improved directivity over its conventional counterpart is presented in this paper for high-speed WiMAX applications, which require unidirectional attributes. The novel structure consists of four log-periodic arms at a wedge pattern, located in pairs on each side of a planar substrate, thus preserving the fabrication simplicity of the single arm configuration. The radiator is thoroughly investigated by means of an efficient 3-D finite-difference time-domain algorithm in an attempt to maximize the directivity, and yet retain the other attractive characteristics of log-periodic antennas. Finally, the optimized device, except for its radiation attributes, is examined with respect to its input impedance and return loss in order to confirm the enhanced levels of directivity.