Planar four-direction antenna for antenna pattern diversity reception

In digital mobile communication, the directional diversity method is useful against fading. In this method, the antennas are switched successively to the antenna directed toward the arrival of the desired signal. In this paper, a four‐directional switching antenna is proposed for the directional diversity. The proposed planar antenna consists of a sectoral patch antenna and 3‐dB hybrids. By means of the cavity model, the eigenvalue, radiation pattern and mutual coupling between the elements are calculated for this antenna. It is shown theoretically that this antenna has the necessary characteristics of a four‐direction antenna. The radiation pattern and the mutual coupling between the elements were measured for the antenna fabricated on a dielectric substrate to confirm the validity of the computation.