Optically Transparent Metasurface Radome for RCS Reduction and Gain Enhancement of Multifunctional Antennas

In this article, we theoretically propose and experimentally demonstrate a compact, optically transparent metasurface radome with asymmetric electromagnetic absorption for making low-radar cross section (RCS) and gain-enhanced multifunctional antennas. The proposed unseeable metasurface has a bilayer structure consisting of periodically patterned and unpatterned transparent conductive films separated by a thin acrylic layer. Such a bilayer metasurface is highly reflective when illuminated by microwave from one side, while exhibit a high absorption when illuminated from the other side. Moreover, when the optically transparent, weather-proofing bilayer metasurface acts as a radome, it can greatly enhance the gain and reduce RCS of the solar panel-integrated microstrip antenna without affecting the performance of optical devices (e.g., photovoltaic panels, flat panel displays, or light emitting devices). We provide the analytical formulation and design guidelines for the bilayer metasurface and the integrated cavity antenna. Our experimental results show that the realized gain of the microstrip antenna can be increased by 6.1 dBi and its RCS can be reduced by more than 20 dB around the operating frequency of 8.1 GHz. The proposed low-profile, flexible, hydrophobic, and optically transparent bilayer metasurface may be beneficial for many applications, including the next-generation radomes, self-powered 5G/6G base stations, satellite communication (CubSat), and other compact, multifunctional RF and microwave modulus integrated with optical sensors, lidar, displays, and solar panels.