Triple-band polarization-insensitive wide-angle ultra-thin planar spiral metamaterial absorber

The design, fabrication, and measurement of a triple-band metamaterial absorber are presented. The proposed absorber consists of a metallic planar spiral layer and a metallic ground plane separated by a dielectric layer. Experimental results show that the proposed absorber can perform absorption peaks at three resonant frequencies 9.86 GHz, 12.24 GHz, and 15.34 GHz with the absorption of 99.4%, 96.7%, and 99.1%, respectively. In addition, the absorber with the thickness of λ/35 at the lowest fundamental resonant frequency can operate at a wide range of incident angles under both transverse electric and transverse magnetic polarizations.