Beamforming Concept for Multi-Beam Antennas Based on Characteristic Modes

A novel beamforming concept for small cells in 5G cellular systems at millimeter wave frequencies is proposed. Base station antenna arrays may be mounted on street lights or similar elevated structures to form small, densely deployed cells. In such a scenario, the power received by a mobile user within a cell depends on the scan angle due to varying directivity and propagation losses which has considerable impact on the base station efficiency. In order to overcome these issues, multi-beam antennas are employed as array elements. Depending on the scan angle, a suitable beam is selected and then steered towards the user. The multi-beam antennas are designed by means of the theory of characteristic modes. The basic feasibility of the proposed concept is demonstrated.