A wide-angle polarization-insensitive ultra-thin metamaterial absorber with three resonant modes

In this paper, we report the design, fabrication, and measurement of a metamaterial absorber that is constructed of a periodic array of tetra-arrow resonators (TARs) printed on a dielectric material backed by a metal ground. The TAR absorber can operate at three different resonant modes. By adjusting geometry parameters of the structure, we can obtain a dual-band, polarization-insensitive, wide-angle thin absorber or a single band but ultra-miniature absorber that corresponds to three different resonant modes. Waveguide experiments are conducted to verify the proposed designs effectively. The measurement results show that all three absorptivity peaks come near to perfection.