Modeling Radiated Emissions From PCBs in Shielding Enclosures Based on A Numerical Green's Function Approach

To accurately and efficiently model the radiated emissions from printed circuit boards (PCBs) placed in shielding enclosures, in this work, a novel approach based on the numerical Green's function (NGF) is proposed. In terms of Schelkunoff's equivalence principle, if the interior of the shielding enclosure is filled up with perfectly electric conductor (PEC), only tangential electric fields over the ventilation slots are sufficient to obtain the radiated emissions. However, due to the presence of the PEC filled shielding box, the in-situ Green's function is not available. To conquer this problem, the proposed approach can be split into two steps. In the first step, the tangential electric fields over ventilation slots are sampled. The NGF over a spherical surface encompassing the perfectly electric conductor (PEC) filled shielding enclosure is obtained by full-wave simulation subsequently. The magnetic field over the spherical surface can be calculated on the basis of the NGF and the sampled electric field. In the second step, the spherical surface is filled up with perfectly magnetic conductor (PMC). The radiated emission outside the spherical surface is predicted according to the previously calculated magnetic field via expanding the Green's function by spherical modal functions. The preponderance of the proposed method in efficiency and versatility is verified by representative numerical examples.