Tailoring the resonances on Fibonacci spiral fractal metasurface for miniaturized multi-band microwave applications

Synthetic fractals have a large potential to achieve tunability and broadband serviceability for multimodal microwave devices owing to their scale-invariant property that generate strongly enhanced local fields with multiscale spatial distributions over multi-spectral ranges. Herein, we demonstrate a microwave metasurface absorber consist of periodic supercells of Fibonacci spiral capable of achieving highly efficient absorptions in a certain bandwidth and several discrete frequencies. Multiple absorption modes are achieved through the synergistic effect of multiple LC-resonances and cross-coupling of the patterned elements, and a broadband operation is completed by adjusting the thickness of dielectric layer based on interface interference theory. Experimental microwave average absorptivity over 82.9% (reflection loss, RL ≤ −7 dB) covering the 10.82–14.18 GHz region is obtained and the maximum absorptivity exceeds 99.8% with sub-wavelength thickness (0.039 λ0 ). These results demonstrate that the synthetic fractal metasurface can be a good candidate absorber for microwave applications like sensing, multiband detecting and filtering.