In this paper, a novel antenna array at 5GHz is presented with a low sidelobe level and wide impedance bandwidth for indoor positioning applications . The antenna array has the size of 450 ×57× mm3 with the high gain of and the low SLL of -18 dB at 5GHz. The sesier feed using Unequal Split T-Junction is proposed with the Chebyshev-amplitude distribution to improve SLL. Besides the 1800 phase and amplitude distribution, by deploying driven elements above each single antenna element, the radiation pattern and the gain of the antenna aray are significantly improved. | Series feed fan-beam antenna array with a low sidelobe level for positioning system