Estimating Reverberant Electromagnetic Fields in Populated Enclosures by Using the Diffusion Model

The ability of an enclosure to protect its contents from electromagnetic interference is quantified by its shielding effectiveness. Previous research has proved that the contents of an enclosure may greatly change the internal field and thus the shielding effectiveness. The power balance method is an efficient approach to analyze shielding problems of populated enclosures. One assumption of the power balance method is that in the steady state, the electromagnetic field in an enclosure is homogeneous. In actual circumstances, however, the presence of losses in an enclosure often compromises the field homogeneity and the power balance method may become inaccurate. A diffusion equation approach has been previously proposed to overcome this problem. In this paper, we predict the internal electromagnetic field of a populated enclosure by using the diffusion model, and compare them with the fields obtained by the power balance method, a fullwave electromagnetic solver and measurements, to demonstrate its efficacy. Comparisons between the diffusion model and the power balance method show that for populated enclosures, the internal electromagnetic field varies with position and that the diffusion model allows this to be observed.