Comment on: 'Wide incidence angle and polarization insensitive dual broad-band metamaterial absorber based on concentric split and continuous rings resonator structure'

Abstract

The subject paper (Agrawal et al 2018 Mater. Res. Express 5, 115801) contains the incorrect assertion that both the effective relative permittivity and the effective relative permeability of an absorbing planar metamaterial structure can be purely real. The claim in the same paper that an optimized metamaterial structure is a broad-band absorber is also incorrect; instead, it is a broad-band linear-polarization converter. © 2019 IOP Publishing Ltd.