Comment on "an ultrathin and broadband metamaterial absorber using multi-layer structures" [J. Appl. Phys. 114, 064109 (2013)]

Abstract

In a recent publication by Xiong et al. [J. Appl. Phys. 114, 064109 (2013)], a linear cross-polarizer is erroneously interpreted as a broadband absorber with a claimed absorptivity above 90% over a frequency range of 8.3721 GHz. In this article, the authors have presented an investigative study demonstrating that the structure proposed by Xiong et al. is actually an efficient cross-polarizer rather than a perfect absorber. If we consider both co- and cross-polarized components of the reflected electromagnetic wave, the subject absorber provides less than 20% absorption in the claimed band. In addition, the polarization conversion ratio of the structure is above 85% within the operating band, this makes the subject metasurface a potential candidate for applications where high-efficiency cross-polarization is desired.