A wrenched-square shaped polarization independent and wide angle stable ultra-thin metamaterial absorber for S-band, X-band and Ku-band applications

Abstract

In this paper, a miniaturized quad-band polarization independent metamaterial loaded ultra-thin absorber is presented. The structure of the proposed absorber designed such that one resonator provides three absorption bands independently albeit another resonator contributes in two absorption bands further combination of mentioned resonators provides four absorption bands. As a result of this proposed metamaterial absorber exhibits four distinct absorption bands with peak absorptivity of 95.75%, 95.93%, 97.69%, and 95.64% at 3.2, 5.32, 11.15, and 16.73 GHz, respectively. The simulated full width at half maximum (FWHM) bandwidths are found as 90 MHz (3.15–3.24 GHz), 220 MHz (5.21–5.43 GHz), 410 MHz (10.94–11.35 GHz), and 700 MHz (16.38–17.08 GHz) correspondingly. Moreover, the designed absorber structure is ultra-thin with a thickness of 0.01 λ0 and unit cell is miniaturized with electrical size of 0.11 λ0 × 0.11 λ0 corresponding to free-space wavelength (λ0) calculated at lowest absorption frequency. The metamaterial characteristic of proposed unit cell has been validated by discussing complex dielectric permittivity, magnetic permeability and dispersion diagrams. Owing to the four-fold symmetry of absorber unit cell structure, it shows polarization insensitive behavior. The proposed ultra-thin absorber can be applied in various applications like stealth technology, imaging, electromagnetic interference suppression, sensing, and wireless applications.