A new exploration of quality testing technique for the wafer-scale graphene film based on the terahertz vector network analysis technology

•Mechanism of surface scattering of THz wave by heterogeneous graphene is proved.•Anisotropic EM properties of linear defects on graphene surface were studied.•Studied a method for testing the uniformity of thickness of graphene.•Studied a method for testing the homogeneity of conductivity of graphene.•Studied a method for testing distribution state of line-shaped defects on graphene.