A beamforming network using a 3-dimensional dielectric lens for SDMA systems

In this paper, we describe a beamforming network we propose that is based on a 3-dimensional (3D) Luneburg lens to generate multiple beams for 2-dimensional space division multiple transmission. This will enable the development of future high-speed and large-capacity wireless systems. The proposed network can generate multiple narrow beams in both the horizontal and vertical directions by its simple one-lens configuration. We also describe an objective function we propose to maximize the area average channel capacity and derive the optimal locations of the network's input ports. To validate the network's theoretical performance, we derived the directivity and calculated the channel capacity at each location by numerical analysis. From the results, we found the optimal spacing angle between input ports is nine degrees when there are 9 × 9 input ports, 19 × 19 output ports, and 10 m × 10 m area size. Using the derived configuration enabled the area average channel capacity to be maximized to 1.8 bits/s/Hz/m 2 .