Investigation of polarization-independent wide-angle metamaterial inspired ISM-band absorber

In this paper, the polarization independent wide angle ISM-band metamaterial absorber structure has been investigated for various geometrical parameters along with the practical demonstration. The presented structure has been numerically simulated using full wave electromagnetic simulator exhibiting absorption peak of 99.42% at 2.48 GHz. The effects of variations in geometrical parameters have been manifested by designing and experimentally verifying two absorber structures with modified parameters, yielding near unity single absorption of 99.89% at 2.4 GHz while dual absorption of 97.2% and 98.1% at 1.76 GHz and 2.48 GHz, respectively. The unit cell of proposed absorber structure comprises of a closed ring resonators engraves on a grounded FR4 dielectric substrate. The simplicity of design imparts effortless fabrication and design symmetry provides polarization insensitivity. Additionally, it has been observed that the proposed structure could achieve high absorption of 90% up to 45 degrees of incident transverse electric wave and up to 60 of transverse magnetic wave attains high absorption of 99%. The optimized absorber structures have been practically demonstrated using waveguide measurement technique and the outcomes are in good agreement with the numerically simulated results.