Semi-empirical modeling of apertures for shielding effectiveness simulations

A novel method to include models of complex apertures into the finite-difference time-domain (FDTD) method is presented. Instead of resolving the geometrical details of the aperture, the aperture is treated as a magnetic dipole. The properties of the magnetic dipole moment are determined using the measured transmission cross section of the aperture. This semi-empirical model permits inclusion of complex apertures in FDTD simulations where the smallest dimension of the aperture is only a fraction of the FDTD cell size. Two types of complex apertures positioned in the top panel of a realistic enclosure have been modeled using the semi-empirical model in FDTD. Comparisons between simulated and measured shielding effectiveness of the enclosure are presented, and the results show that complex apertures can indeed be represented by simple magnetic dipoles in shielding effectiveness simulations.