Abstract
In a recent article, Wang et al. [J. Appl. Phys. 116, 094504 (2014)] proposed an ultra-thin broadand microwave metamaterial absorber and claimed the absorption above 90% in the operating band of 8.85 GHz-14.17 GHz. In this comment, we argue that the authors have neglected the cross-polarized reflection in their calculation of absorption. The proclaimed anisotropic pentagon patch metamaterial is predominantly a cross polarizer for the normally incident electromagnetic wave. We demonstrate that the actual absorption of the metamaterial structure remain less than 40%. Hence, the proposed metamaterial is not a perfect broadband absorber; however, it can be used as an efficient crosspolarizer. Published by AIP Publishing.