2-D Luneburg Lens Beamforming Network for Planar Phased Array of Antennas to Radiate Near-Field Focused Multibeams

In this article, a two-dimensional (2-D) Luneburg lens-based beamforming network (LL-BFN) realizable on parallel-plate-sandwiched substrates is implemented to excite a planar phased array of antennas for near-field focus (NFF) applications of multibeam radiations. The concept is to select a proper position of a cylindrical ring surrounding the 2-D Luneburg lens and intercept the phases on this ring to excite the antenna array for NFF multibeam radiations. The intercepted phases are consistent to that required to excite a planar array for NFF radiation. Due to the circular symmetry characteristics of LL-BFN architecture, the distribution of the resulted multibeams exhibits a spatial shift of focal points when the lens is excited by angularly shifted ports on the LL-BFN. The concept is developed with both the numerical and experimental results shown to validate the feasibility of LL-BFN architecture. Practical implementation of low cost is demonstrated.