A Narrow Beam Steering Antenna Array for Indoor Positioning Systems Based on Wireless Sensor Network

Abstract

This paper proposes the 2.45~GHz planar Beam Steering Antenna Array for Indoor Positioning Systems. The antenna array consists of a phase shifter based on a 4times 4 Butler matrix, and an array of four dipole Yagi antennas. By choosing one of four beams using a switching controller, the main beam of the antenna can steer in four directions from +37°, -12°, +12° to -36°. The antenna has a narrow fan beam with a beamwidth in the azimuth plane of from +21.5° to +24.5° and in the elevation plane of approximately 90° which effectively minimizes multipath signals. These advantages are suitable for positioning systems to increase location accuracy. The antenna achieves a peak gain of from 9.1 to 9.8~dBi in four directions, a wide band of 400~MHz. The fully electronically steerable antenna prototype has been designed using CST software, simulated based on the finite element method, and fabricated on the RO4003C substrate as well as measured. The antenna is implemented in the Indoor Positioning System using three different location methods, including trilateration, triangulation, and fingerprinting, to highlight the antenna's advantages in improving location accuracy with the ratio between the mean location error and area of 0.051, 0.033, and 0.023 respectively.