Enhancing and tuning absorption properties of microwave absorbing materials using metamaterials

We proposed and demonstrated a scheme to enhance and tune absorption properties of conventional microwave absorbing materials (MAMs) by metamaterials (MMs). By covering a MAM, say, carbonyl iron powder coating, with MMs composed of split ring resonators (SRRs) and wires, we show both by experiments and by simulations that the maximum reflection loss (RL) is increased significantly and the frequency region for absorption is shifted to lower frequency. The frequency region in which the maximum RL is less than −10 dB shifts from 5-7 to 4.2-6.2 GHz for perpendicular polarization electromagnetic waves and to 4-9 GHz for parallel polarization waves. Simulation results reveal that the magnetic resonance obtained by SRRs and the electric resonance obtained by copper wires are the main factors in enhancing and tuning microwave absorption properties.