The three beam-switched top-loaded antenna is suited to be applied to a wireless local area network to switch the radiation pattern by arranging several unidirectional antennas. In this paper, a three beam switched top loaded monopole antenna is proposed to realize its small size and planar structure. Three top loaded monopole antennas are arranged around a parasitic hexagonal patch at intervals of 120 degrees. The feed element is selected by the switching device to switch the radiation pattern. This antenna allows for reduction in the number of elements as well as downsizing. The front to back ratio (F/B) becomes 23 dB by selecting suitable parameters.

This paper proposes a 2.6 GHz low cost DBF array antenna system and reports its evaluation based on our experimental results. The proposed system is partially constructed by digital devices for the simplification of hardware, and employs some techniques for improving the resolution. The system is evaluated through the DOA estimation by the MUSIC algorithm inside a radio anechoic chamber. As a result, we found that the proposed system estimates the DOA with the highest accuracy at which MUSIC algorithm can perform. Moreover, this paper discusses the estimation errors. We also found that the estimation error is particularly affected from the inaccurate element interval.