Flat‐Knit, Flexible, Textile Metasurfaces

Abstract

Lightweight, low‐cost metasurfaces and reflectarrays that are easy to stow and deploy are desirable for many terrestrial and space‐based communications and sensing applications. This work demonstrates a lightweight, flexible metasurface platform based on flat‐knit textiles operating in the cm‐wave spectral range. By using a colorwork knitting approach called float‐jacquard knitting to directly integrate an array of resonant metallic antennas into a textile, we realize two textile reflectarray devices, a metasurface lens (metalens) and a vortex‐beam generator. Operating as a receiving antenna, the metalens focuses a collimated normal‐incidence beam to a diffraction‐limited, off‐broadside focal spot. Operating as a transmitting antenna, the metalens converts the divergent emission from a horn antenna into a collimated beam with peak measured directivity, gain, and efficiency of 21.30 dB, 15.30 dB, and –6.00 dB (25.12%), respectively. The vortex‐beam generating metasurface produces a focused vortex beam with a topological charge of m = 1 over a wide frequency range of 4.1‐5.8 GHz. Strong specular reflection is observed for our textile reflectarrays, caused by wavy yarn floats on the backside of the float‐jacquard textiles. Our work demonstrates a novel approach for scalable production of flexible metasurfaces by leveraging commercially available yarns and well‐established knitting machinery and techniques.This article is protected by copyright. All rights reserved