Dielectric and Ohmic losses in perfectly absorbing metamaterials

We investigated two mechanisms of the heat generation to enhance the absorption peak of metamaterials (MMs) at the normal incidence of electromagnetic radiation. The metal-dielectric-metal sandwich-type model, in which an array of copper squares at the front and a copper plane at the back were separated by a dielectric layer, was studied for GHz frequencies. Firstly, we studied the effect of the thickness of copper square to obtain the absorption peak. The obtained results showed that absorption can be enhanced to be nearly 100% at 16 GHz by increasing the sheet resistance of the copper square. In this case, the Ohmic-loss perfect-absorption (PA) MM was devised. The PA effect was also achieved by using the loss-tangent of dielectric layer as a dissipation factor. For this purpose, we studied complex the dielectric constant of dielectric layer. The PA peak was demonstrated at the same frequency. In the second case, the dielectric-loss turns out to be dominant. The comparison between TE and TM polarizations for the PA peaks was also elucidated. (C) 2013 Elsevier B.V. All rights reserved.