Effective boundary conditions for the time-domain analysis of the EMC performances of fiber composites

An efficient model is proposed for the analysis of the shielding performances of fiber reinforced composites against transient electromagnetic plane waves. The non-homogeneous material is simulated by an equivalent non-uniform anisotropic slab, characterized by proper tensors of effective permittivity and conductivity. The analysis of the field propagation through the effective panel is carried out in the frequency-domain, in order to compute the transmission and surface impedance matrices of the panel. The time-domain effective boundary conditions, which describe the relations among the TE and TM field components tangential to the external faces of the slab, are expressed in terms of the transient transmission and surface impedance matrices. The model is implemented in a three-dimensional finite-difference time-domain procedure and is applied to the analysis of the field penetration inside a composite box illuminated by an impulsive plane wave