Design of metamaterial absorber based on resonant magnetic inclusion

Artificially structured electromagnetic (EM) materials have become an extremely active research area because of the possibility of creating materials which exhibit novel EM responses not available in natural materials. In addition, microwave absorbers are used in military applications to reduce the radar cross section (RCS) of a conducting object and the EM interference among microwave components. Recently, absorber technology has seen several advancements with the use of artificially structured metamaterials (MTMs) for creating a high-performance absorber for the microwave and terahertz frequency regimes [1-2]. MTMs can be represented by the complex values of electric permittivity and magnetic permeability. This permittivity and permeability can be independently controlled by varying the dimensions of the electric and magnetic components. Additionally, an MTM can be impedance-matched to free space by tuning the electric and magnetic resonances, resulting reflectivity R = 0. The additional multiple layers or metallic back-plate will also ensure transmission T = 0. As a result, 100 % absorbance A (= 1 - R - T) is theoretically possible. Typically, absorbers contain metallic backing plates [3-4] for avoiding power transmission through the absorbers, which may be disadvantages in stealth applications. In order to eliminate the use of metallic backing plates, the multiple split ring resonators (SRRs) based on resonant-magnetic inclusions are used [5]. However, the absorber requires a resistive sheet placed at a certain distance from the MTM slab in order to match the impedance of free space. In this work, we present a new type of a double-negative MTM absorber based on resonant-magnetic field inclusion. In contrast to common absorber configurations, the absorber proposed in this paper does not involve a metallic back plate or a resistive sheet.