Anisotropy Characterization of Metallic Lens Structures

Abstract

This paper presents a full electromagnetic (EM) characterization of metallic lenses. The method is based on the utilization of free-space transmission and reflection coefficients to accurately obtain lenses’ tensorial EM parameters. The applied method reveals a clear anisotropic behavior with a full tensorial directional permittivity and permeability and noticeably dispersive permeability and wave impedance. This method yields accurate values for the effective refractive index, wave impedance, permittivity, and permeability, unlike those obtained by simple methods such as the eigenmode method. These correct cell parameters affect their lens performance, as manifested in a clear level of anisotropy, impedance matching, and losses. The effect of anisotropy caused by oblique incidence on the performance and operation of lens designs is illustrated in a lens design case.

A Wideband GRIN Dielectric Lens Antenna for 5G Applications

“…For forming lenses in the microwave and sub-terahertz regimes, metallic parallel-plate waveguide structures are considered the simplest periodic artificial sub-wavelength structures with a graded effective refractive index (GRIN) [ 9 ]. However, metallic lenses show anisotropic behavior, have a narrow bandwidth and are costly and complex [ 10 ]. GRIN materials are materials in which the refractive index changes gradually as a function of position within the material.…”