All-metal wideband metasurface for near-field transformation of medium-to-high gain electromagnetic sources

• Published in: Scientific reports Vol. 11; no. 1; pp. 9421 - 9
• Main Authors: Lalbakhsh, Ali, Afzal, Muhammad U., Hayat, Touseef, Esselle, Karu P., Mandal, Kaushik
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.05.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/166/987; 639/766/1130/2798; Antennas; Humanities and Social Sciences; Metals; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-88547-3

Electromagnetic (EM) metasurfaces are essential in a wide range of EM engineering applications, from incorporated into antenna designs to separate devices like radome. Near-field manipulators are a class of metasurfaces engineered to tailor an EM source’s radiation patterns by manipulating its near-field components. They can be made of all-dielectric, hybrid, or all-metal materials; however, simultaneously delivering a set of desired specifications by an all-metal structure is more challenging due to limitations of a substrate-less configuration. The existing near-field phase manipulators have at least one of the following limitations; expensive dielectric-based prototyping, subject to ray tracing approximation and conditions, narrowband performance, costly manufacturing, and polarization dependence. In contrast, we propose an all-metal wideband phase correcting structure (AWPCS) with none of these limitations and is designed based on the relative phase error extracted by post-processing the actual near-field distributions of any EM sources. Hence, it is applicable to any antennas, including those that cannot be accurately analyzed with ray-tracing, particularly for near-field analysis. To experimentally verify the wideband performance of the AWPCS, a shortened horn antenna with a large apex angle and a non-uniform near-field phase distribution is used as an EM source for the AWPCS. The measured results verify a significant improvement in the antenna’s aperture phase distribution in a large frequency band of 25%.