Angle of Arrival Measurement Using Multiple Static Monopole Antennas

The angle of arrival (AoA) is an important factor in the localization of a wireless sensor network. This paper deals with AoA measurement using omnidirectional antennas. In our case, microstrip monopole antennas are used, which have radiation patterns with two sharp minimums. Therefore, an algorithm based on an approach where an AoA is obtained along a direction where the measured received strength signal indicator is minimal. Multiple stationary microstrip antennas are placed on a printed circuit board and no moving parts are needed for measurement. In comparison with rotating antennas this simple method has lower resolution. We show that the resolution can be improved using interpolations and approximations. When using the proposed algorithm, the experimental results for the outdoor measurements reached a root-mean-square error of <10 degrees, and an indoor environment of <25 degrees.