Uniplanar 2-D Butler Matrix for Multibeam Arrays

A 2-D Butler matrix (BM) in uniplanar configuration for designing multibeam array antenna (MAA) is proposed using substrate integrated waveguide (SIW) technology. Firstly, a novel topology for building uniplanar 2D BM is proposed, which successfully transforms the traditional 3-D topology to a 2-D (or uniplanar) one. To realize the planarization of basic components, a novel design of eight-port hybrid couplers, is developed to transform four spatially intersected couplers to a planar structure. To address the issue of excessive path intersections, a novel SIW eight-port crossover is proposed to reduce the number of path intersections from 16 to merely 4. Using this proposed 2-D BM, a 2-D MAA with 16 (4 × 4) beams can be realized.