Six band metamaterial absorber designed on twisted square and swastika-shaped resonator for S, C, X, and Ku band frequency and sensing applications

Abstract A twisted square split ring and swastika resonator (TSSRSR) based six-band polarization-insensitive metamaterial absorber (MMA) with high effective medium ratio (EMR), and excellent absorption is proposed in this study. It can be utilized as an S, C, X, and Ku band frequency absorber and as a sensor at 6.38 GHz (C-band). A swastika geometry-based unique patch has been introduced in the proposed unit cell to achieve high polarization insensitive properties with excellent absorption of 90%, 96.5%, 91.7%, 90.7%, 95.6%, and 91.7% respectively under S, C, X, and Ku band frequency spectrum. The distinctive features of this proposed TSSRSR unit cell are its simple, unique structure with a high EMR value of 8.06, and polarization-insensitive up to 90 ∘ at 3.72, 6.38, 10.76, 15.28, 18.84, and 21.08 GHz respectively. The designed MMA unit cell is fabricated on a loss FR-4 dielectric substrate with an electrical dimension of 0.124 λ 0 × 0.124 λ 0 × 0.157 λ 0 . The angular insensitive properties of the unit cell were also investigated for a maximum angle of 90 ∘ for TE and TM mode. Moreover, the unit cell and array structure performance exhibits a maximum absorption of > 90%, suitable for sensing and antenna systems. The simulated outcome is verified by experiment with excellent accordance. The suggested MMA is very attractive for refractive index sensing applications due to several features, including its low profile, excellent angular stability, polarization insensitivity, sensitivity, quality factor (Q), figure of merit (FOM), and EMR value.