Double-corrugated metamaterial surfaces for broadband microwave absorption

Double-corrugated metamaterial surfaces are proposed to achieve broadband absorbers in the microwave region. The principal corrugation having a long period is made of hypo-corrugated metal structures filled with a dielectric medium. It is shown that the incident electromagnetic wave with a certain frequency can be strongly absorbed by the corrugation region where the height is about lambda/4, with lambda being the corresponding wavelength in the dielectric. Assembling various heights of corrugations together to form a graded corrugation surface can excite many distinct absorption modes and their overlapping with each other results in a broadband absorption. We experimentally demonstrate a broadband metamaterial absorber with more than 80% absorbance in the frequency range of 7.22-18.0 GHz which agrees well with the numerical simulation. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4793631]