An ultra-thin triple-band polarization-insensitive metamaterial absorber for S, C and X band applications

Abstract

In this paper, a polarization-insensitive triple-band metamaterial absorber is proposed for wide angle of incidence. The proposed absorber has been designed in such a way that absorptions occur in S, C and X bands at 3.1, 4.6 and 9.5 GHz, respectively. The unit cell consists of two modified square-shaped closed-loop resonators printed on top of a dielectric substrate and backed by a complete copper lamination. The proposed structure is ultra-thin having a total thickness of 1.6 mm, approximately \(\lambda _{0}/61\), \(\lambda _{0}/41\) and \(\lambda _{0}/20\) with respect to absorption frequencies in various bands, where \(\lambda _{0}\) is the free space wavelength. Moreover, the structure shows good absorptions over wide angle of incidence up to 45° for both TE- and TM-polarized waves. Surface current and electric field distributions have been studied to analyse the absorption mechanism of the proposed absorber. Parametric analyses have also been carried out for suitable selection of absorption frequencies. Finally, a prototype of the absorber has been fabricated and experimentally tested in order to validate the simulation results which are in good agreement.