A dual resonator-based polarisation-independent dual-band metamaterial absorber

摘要

This article presents an investigation on the design of polarisation-independent dual-band ultra-thin metamaterial absorber for X-band applications. The proposed unit cell is the combination of two resonators named as Resonator-I and Resonator-ll. Both the resonators are designed on the top of FR4 epoxy dielectric substrate with completely metal laminated on the bottom side. The designed absorber structure offers a great amount of miniaturisation with a footprint area of 0.17λ_0 × 0.17λ_0 × 0.017λ_0; here, λ_0 is the free space wavelength with respect to lowest absorption peak. The proposed absorber structure shows two absorption peaks of 99.76% and 95.85% with FWHM (Full Width at Half Maximum) bandwidth of 340 MHz (8.34-8.68 GHz) and 540 MHz (9.76-10.30 GHz) at the frequencies of 8.51 and 10.03 GHz, respectively. Further, the absorptivity of the designed structure has been investigated under distinct oblique and polarisation incidence angles. In order to explain the mechanism of absorption of the proposed absorber structure, electric field distribution, surface current distribution and input impedance plot have been studied. The fabrication and measurement for designed absorber structure have been carried out to verify the simulation results. The designed absorber structure can be suitably used for defence-related ultra-thin applications.