3-D Diffusion Models for Predicting Reverberant Electromagnetic Power Density in Loaded Enclosures

The power balance technique for the prediction of shielding effectiveness of reverberant enclosures is fast and simple to use. However, it assumes a uniform field in the enclosure, which has been shown to be incorrect in the presence of dissipative contents. The diffusion model is a generalization of the power balance method that can account for the field inhomogeneity due to the presence of losses with much lower computational effort than a full-wave solver. Evaluation of a two-dimensional diffusion model produced promising results compared to physical measurements. Here, we present a three-dimensional (3-D) diffusion model applied to an enclosure with an aperture and dissipative contents. Comparisons between the 3-D diffusion model, measurements, and a full-wave solver suggest that it is able to account for the variation of the electromagnetic field due to dissipative contents with far less computational effort than full-wave solvers. The diffusion model allows rapid solution of the shielding effectiveness of enclosures with dissipative contents and arbitrary geometries and reduces the time to model equipment enclosures from hours to minutes, while still determining the variation of field strength due to contents. In addition, the method may help predict field inhomogeneity in reverberation chambers.