Abstract: A novel planar beam steering parasitic array of planar printed dipoles is proposed, which can be used in the mobile terminals to improve communication quality and system capacity. The main beam can be controlled by the reactive loads on the parasitic elements. The antenna prototype is designed using the software based on the full wave analysis and the loaded reactance values are optimized by the Differential Evolutionary (DE) algorithm. The measured results show that the main beam can be steered from -34~38 in the xoy plane. At every main radiation direction, the gain at the center frequency is from 3.6~4.9 dBi and the bandwidth of the reflection coefficient less than -10 dB is 330 MHz, which is from 5.63~5.96 GHz. The proposed antenna has good beam steering performance and the optimum design method is accurate and efficient.