A Compact Broadband High-Efficiency Planar-Lens Antenna Based on Ultrathin Huygens' Metasurface

In this letter, we investigate a high-gain planar lens antenna based on Huygens' metasurface (HMS). This design features high aperture efficiency (AE) and a broadband frequency response, effectively addressing the issues of large size, heavy weight, and narrow bandwidth commonly associated with conventional high-gain antennas. We present a compact broadband y-polarized HMS unit with a profile thickness of 0.096<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ \lambda _{0}$</tex-math></inline-formula>. The design process of this broadband metasurface (MS) unit is described in detail, elucidating the mechanism of Huygens resonance generation from the gap between anisotropic and isotropic structures, and providing a novel approach to broadband HMS design. In order to evaluate the performance of this antenna, we performed full-wave simulation, processing and testing of the proposed lens. The measurement results show that the HMS-Lens has good radiation performance in the range of 12.7 to 16.1 GHz and achieves a peak gain of 28.93 dBi with a sidelobe level (SLL) greater than 20 dBi at 14.8 GHz. The AE of the antenna is 55.29% with a 3 dB gain bandwidth (GBW) of 23.6% and a 1 dB GBW of 13.89%. Comparison with various state-of-the-art MS-based lens antennas shows that the proposed HMS-Lens design outperforms them in terms of operating bandwidth, aperture efficiency, profile thickness, compactness, complexity and radiation performance.