Dendritic-metasurface-based flexible broadband microwave absorbers

Based on the dendritic metasurface model, a type of flexible and lightweight microwave absorber (MA) comprising resistance film array with dendritic slot (RFADS), dielectric material, and metal plate is proposed. A broadband absorptivity of >80% is obtained both from simulation and experiment at frequency ranges of 3.0–9.2 and 3.2–9.00 GHz, respectively. And the thickness of MA is 5 mm, which is only 0.05λ_low, or 0.15λ_high, where the λ_low and the λ_high are the beginning and the end of the working frequency. By combining this metasurface-based MA with the dendritic-resistance-film-based microwave metasurface absorber (MMA), we designed a broadband MMA. The simulations and experiments showed that this kind of MMA can absorb the radiation effectively at a wide frequency range 4.5–17.5 GHz. And the thickness of this combined MMA is 4 mm. All the structures showed their insensitivity to the incident angle (0^∘–40^∘) and the polarization of the incident wave because of their structural symmetry. In addition, the small thickness, low apparent density, and flexibility made those structures possess the advantages of being applied in microwave stealth and radar cross-section (RCS) reduction.