Planar Multibeam Array Antenna with Rotman Lens Beamformer for 5 GHz Band Wireless Applications

A planar multi-beam array with a co-planar rotman lens beamformer is introduced for wireless applications. the array consists of 8 linear series-fed subarrays with proximity-coupled patch elements. the rotman lens feeds the subarrays through coupling slots. to reduce beam squinting, the subarrays are fed from the center. the coupling slot feeds each arm of a subarray 180° out of phase. to compensate out-of phase feeding, two feeding arms of each subarray are designed in the opposite direction. also, cross-polar radiation is reduced significantly. in order to reduce the size of radiating patches to fit within array cell size, they are formed by four sub-patches with indentions and are fed by microstrip line from feed layer with two matching sections to improve the bandwidth. measured results of the array structure in terms of the s-parameter of beam ports and radiation patterns are presented.