Material-structure collaborative design for broadband microwave absorption metamaterial with low density and thin thickness

There is a great demand for the metamaterials with low density, thin thickness and broadband microwave absorption in the aeronautic stealth domain. However, it is still a great challenge to achieve satisfactory impedance matching between free space and metamaterials subjected to above constraints. To address this issue, a material-structure collaborative approach was proposed for designing excellent microwave absorption metamaterial with low density and thin thickness, which includes nanomaterial synthesis, unit cell optimal design and absorption mechanism analysis. The 3D Graphene-Carbon nanotubes-Nickel nanomaterial was firstly synthesized by in-situ growth method for fabricating the low-density metamaterial. Inspired by the natural anti-reflection microstructure of Polygonia c-aureum's eye, the unit cell of metamaterial was designed. Size parameters optimization of designed unit cell was conducted with the efficient immune genetic algorithm. The optimized metamaterial is extremely advantageous in effective absorption bandwidth (EAB, reflection loss ≤ −10 dB), low density and thin thickness, which can achieve 29.1 GHz EAB and equivalent density as low as 0.65 g/cm³ (the areal-density is 3.58 kg/m²) with thickness of only 5.5 mm. The proposed material-structure collaborative approach provides an efficient and systematic avenue for designing broadband microwave absorption metamaterials.