A wireless communication method and antenna system for determining the
direction of arrival (DOA) of received signals in azimuth and elevation,
(i.e., in three dimensions), to form a beam for transmitting and
receiving signals. The system includes two antenna arrays, each having a
plurality of antenna elements, two first stage multi-mode-port matrices,
at least one second stage multi-mode-port matrix, an azimuth phase
detector, an elevation amplitude detector, a plurality of phase shifters
and a transceiver. The antenna arrays and the first stage multi-mode-port
matrices form a plurality of orthogonal omni-directional modes. Each of
the modes has a characteristic phase set. Two of the modes' phases are
used to determine DOA in azimuth. The second stage multi-mode-port matrix
forms a sum-mode and a difference-mode used to determine the DOA of the
received signals in elevation. A beam is formed in the direction of the
received signals by adjusting the phase shifters.