Flat‐Knit, Flexible, Textile Metasurfaces

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, two textile reflectarray devices, a metasurface lens (metalens), and a vortex‐beam generator are realized. 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, 15.30, 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 the textile reflectarrays, caused by wavy yarn floats on the backside of the float‐jacquard textiles. This work demonstrates a novel approach for the scalable production of flexible metasurfaces by leveraging commercially available yarns and well‐established knitting machinery and techniques. This work demonstrates a lightweight, flexible metasurface platform based on flat‐knit textiles and 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, two textile devices are realized, a metasurface lens and a metasurface vortex‐beam generator.