Subcell FDTD Modeling of Field Penetration Through Lossy Shields

A new subcell finite-difference time-domain model is presented to solve shielding problem. The field penetration through the nonperfectly conductive shield is modeled by two-port network equations in terms of frequency-dependent admittances which are rationalized by the vector fitting procedure. The resulting equations are used to synthetized an equivalent linear time invariant circuit which is analyzed directly in time domain without using convolution equations. This important aspect is the main novelty of the proposed procedure.