Multilayer graphene-coated honeycomb as wideband radar absorbing material at radio-frequency

In this work we analyze the feasibility of a broadband radar absorbing material made with an aeronautical grade honeycomb panel, coated with a thin conducting film of multilayer graphene nanoplatelets (MLGs). The film is deposited over the surface of a phenolic-aramid sheet and characterized in terms of sheet resistance and thickness. The morphology of the multilayer graphene flakes is analyzed by atomic force and scanning electron microscopies. The deposition parameters are optimized in order to control the sheet resistance of the conducting MLG film. The microwave broadband radar absorbing properties of a MLG-coated phenolic-aramid honeycomb panel are predicted through 3D electromagnetic simulations. It is shown that with a panel thickness of 10 mm and a sheet resistance of the MLG coating of 1238 Ω/□, the reflection coefficient RdB has a minimum at ~9 GHz. Moreover, it results that the absorbing panel is broadband, with RdB ≤ -10 dB in the range from 5.5 GHz to 27 GHz.