All-Metallic-Metasurface-Based Wideband Dual Fabry–Perot Resonance Antenna Array With High Directivity and Polarization Purity

In recent years, the integration of metasurface concepts into antenna design has sparked a revolutionary breakthrough, yielding unprecedented advancements in directivity, bandwidth, radiation pattern, polarization, and beam shaping capabilities once thought unachievable. However, further enhancements are still necessary, particularly in terms of integrability and loss reduction, while simultaneously broadening the operational bandwidth and enhancing gain and directivity. In this work, we demonstrate that incorporating the gap-waveguide (GW) technology into the radiator section can be leveraged to improve bandwidth and directivity of antenna arrays, mimicking a dual perfect electric conductor–perfect magnetic conductor (PMC) Fabry–Perot (FP) resonant cavity. Importantly, our concept comprises an entirely metallic $4 \times 4$ metasurface-based antenna array, diverging from prior research that employed dielectric components in metasurface design. As a result, the measured bandwidth was around 21% (12–14.8 GHz) with a measured gain of up to 22.9 dBi. Furthermore, we implement GW technology in the feeding layer, directly coupling it to the radiating layer through slots, thereby optimizing the footprint.