Beamforming Phased Array Antenna toward Indoor Positioning Applications

Abstract

Indoor positioning systems based on radio wave have drawn a lot of research interest over the last few decades. One of the positioning methods, Angle of Arrival, locating object based on the relative angle of object to the reference points, requires a directional antenna in order to improve the accuracy of indoor positioning system. From this situation, an eight-port phased array antenna using reflection type phase shifter is designed. The input power is split to each antenna through eight-port Wilkinson power divider with insertion loss of about 11 dB and isolation of about 20 dB. To extract more accurate position, the main beam of phased array antenna can be steered smoothly by a design 18 of a continuous and full 360° reflection type phase shifter with low insertion loss variation. Microstrip patch antennas are used as elements in phased array antenna. The steering of main beam is presented by radiation patterns of phased array antenna, measured in anechoic chamber from
45 to 45° with step 5°. The measurement result shows that the main beam direction is quite close to the desired direction in simulation. In most case, the side lobe level is less than the main lobe about 10 dB.