Flexible Ultrathin Incident-Angle Insensitive Metamaterial Absorber for Curved Surfaces

In this paper, a flexible ultrathin metamaterial absorber has been presented in X-band frequency range. Teflon substrate has been used as a dielectric, hence the proposed absorber offers flexibility and elastic nature. Simulated single-band absorptivity of 99.7% has been achieved at 10.28 GHz frequency with 188 MHz half power bandwidth. The 10-dB bandwidth of the proposed absorber is 60 MHz. Such narrow bandwidth is because of the use of very thin dielectric substrate. Proposed structure exhibits more than 80% absorptivity from 0° to 60° incident angles. Therefore, the designed conformal absorber exhibits higher absorption rates even for highly curved surfaces. The entire thickness of absorber is 0.17 mm (almost 1/170th of resonant wavelength). Permeability and permittivity plots are shown to prove the metamaterial property. Equivalent circuit and dielectric loss tangent plot of the designed absorber have also been shown for further analysis. The parameters present in the equivalent circuit have been extracted and then it is implemented in Advanced Design System (ADS). Finally, ADS results have been compared with High Frequency Structural Simulator (HFSS) results for reflection coefficient of the proposed absorber.