Wideband and High-Gain Folded Transmit-Array Antenna Based on 3-Bit FPTP Metasurface

Abstract

Metasurfaces provide an unprecedented capability for manipulating electromagnetic waves. In this study, a wideband and high-gain folded transmit-array antenna (FTA) based on a 3-bit Fabry–Perot transmission polarizer (FPTP) metasurface was proposed and realized. The proposed FTA comprises three key components: (1) top-layer FPTP metasurface, (2) bottom-layer miniaturized waveguide horn feed, and (3) reflector array. The FPTP metasurface adopts a sandwich structure, integrating two orthogonal metallic grids with an embedded 3-bit digitally encoded C-shaped ring, which simultaneously achieves polarization conversion and high-precision phase compensation while avoiding insertion losses caused by multilayer stacking. The feed employs a customized miniaturized waveguide horn, and the reflector incorporates a 90° polarization conversion function, effectively mitigating the impact of missing central elements in the primary reflector without requiring additional polarization layers. Through synergistic optimization of the FPTP metasurface, feed, and reflector, the system achieves high-gain and wideband performance while maintaining a low-profile geometry (thickness reduced to one-quarter of the focal length). A prototype with 45 × 45 unit cells was fabricated and tested, demonstrating an operational bandwidth of 11.3–17 GHz, a measured peak gain of 27.1 dBi, a 3-dB gain bandwidth of 36.4%, and an aperture efficiency of 38%, all of which align closely with simulations. The proposed 3-bit FPTP metasurface provides a novel solution for low-profile, high-gain antenna design and is expected to find potential applications in next-generation wireless communication systems.