$Ka$ -Band Fully Metallic TE40 Slot Array Antenna With Glide-Symmetric Gap Waveguide Technology

Gap waveguide has recently been proposed as a low-loss and low-cost technology for millimeter-wave components. The main advantage of the gap waveguide technology is that the microwave components can be manufactured in two metallic pieces that are assembled together without electrical contact. The leakage through a thin air gap between the two pieces is prevented by a 2-D periodic structure offering an electromagnetic bandgap (EBG). This EBG is conventionally implemented with metallic pins. Here, we propose the usage of a holey glide-symmetric EBG structure to design a <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> slot array antenna that is fed with a TE₄₀ mode. The TE₄₀ excitation is designed based on a TE₁₀–TE₂₀ mode converter whose performance is initially evaluated by radiation pattern measurements. The final antenna, the <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> slot array antenna, was manufactured in aluminum by computer numerical control (CNC) milling. The antenna has a rotationally symmetric radiation pattern that could find application as a reference antenna as well as for 5G point-to-point communications.