Perpendicular-Corporate Feed in Three-Layered Parallel-Plate Radiating-Slot Array

We propose a perpendicular-corporate feed in a three-layered parallel-plate radiating-slot array to remove the x-shaped cavity walls completely in the radiating part of the conventional planar corporate-feed waveguide slot array antenna. Coupling apertures on the bottom excite radiating slots spaced with the half of their spacing on the middle in the parallel plates. We place dielectric with proper permittivity in the region between the coupling aperture and the radiating-slot layer to excite a standing wave strongly there for a large number of slots. A parasitic-slot layer is added on the top to improve the bandwidth. A 16 × 16 slot array antenna is designed for uniform excitation with the perpendicular and the planar corporate feeds, and fabricated in the 60 GHz band. At the design frequency of 61.5 GHz, the measured directivity is 33.5 dBi with the aperture efficiency of 90.6%.