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A metamaterial absorber with direction-selective and polarisation-insensitive properties

This paper reports the design of a metamaterial absorber with direction-selective and polarisation-insensitive property. Both theoretical and simulated results reveal that the absorber has a distinct absorption point with direction selectivity at 7.48 GHz, which is related to the resonance of the metamaterial and is not influenced by the polarisation. The retrieved impedance indicates that the impedance of the absorber can be tuned to approximatively match the impedance of the free space on one side and not to match the impedance of the free space on the other side. This design can result in the minimal reflectance, the minimal transmission and the highest absorbance at the absorption frequency. The distribution of the power loss indicates that the absorber is an excellent electromagnetic wave collector: the wave is first trapped and reinforced in certain specific locations, and then mostly consumed. The distribution of the surface current is consistent with the design, the retrieved impedance and the distribution of the power loss. This absorber may have applications in many scientific and technological areas.