Focusing millimeter waves using a zoned fishnet metalens

An all-metallic plano-concave zoned lens based on the fishnet metamaterial is designed and experimentally demonstrated at the V-band of millimeter waves. By applying the zoning technique the volume of the lens is reduced considerably up to 60% compared with a complete profiled lens. The lens is designed to work as a near-zero-refractive index medium (n=-0.25) at f=56.7GHz (λ
₀
=5.29mm ) demonstrating an experimental focal length of 8.79λ
₀
and a full width at half maximum (FWHM) of 0.67λ
₀
with good agreement with simulation results.