Analysis and optimization of a wideband metamaterial absorber made of composite materials

Using structural composite materials for the fabrication of Radar Absorbing Materials (RAM) allows combining the strong load bearing capability with the radar absorbing functionality in a unique structure. This article shows the possibility to transpose an already existing metamaterial absorber to the domain of composite materials. The dielectric layers of the absorber initially designed with radio-frequency (RF) materials are replaced with fiber-reinforced composite materials classically used for naval applications that have been specially manufactured and characterized. The working principle of the absorber is explained in detail by analyzing the influence of each layer on the operating frequency band. The performances of the re-optimized composite absorber are compared against the initial RF design and other classical absorbers. The composite design has a total thickness of 8.9mm and achieves a reflection coefficient below -14dB within the band 4.6-17.2GHz at normal incidence. The reflection coefficient remains under -10dB at oblique incidence up to 45 degrees.