Multibeam Radiations From Circular Periodic Array of Vivaldi Antennas Excited by an Integrated 2-D Luneburg Lens Beamforming Network

An antenna array is developed to radiate angularly distributed multibeams. The proposed antenna utilizes a 2-D Luneburg lens as a beamforming network (LL-BFN) to produce rotationally symmetric excitations. The concept is to replace an equivalent circular aperture of Luneburg lens by a circular array of excitation output ports. Thus, in addition to the beam selection ports, antenna excitation ports are also established on the LL-BFN to extract the required phases to feed an external circular array of antennas. As a result, more flexible radiation characteristics can be achieved by the circular array. This concept is demonstrated by both simulation and measurement results of an antenna prototype to validate the feasibility.