Double-Layer Waveguide Planar Array Antenna Composed of E-Plane Feeding Circuit and Narrow-Wall Cavity $2\text{x}2$-Element Sub-Arrays

A 16x16 element array antenna is composed of an E-plane waveguide parallel-feeding circuit in the lower layer and 2x2 slotted narrow-wall cavities in the upper layer. The antenna consists of three plates fabricated by plastic molding with metal plating and is assembled at the center of the broad wall of the waveguide. This structure achieves low-loss property and wide bandwidth simultaneously. The simulated bandwidth with reflection lower than -10 dB was wider than 11 GHz. The gain was 30.5 dBi at 73.5 GHz.