Permeability and permittivity uncertainty effects in modeling absorbing coatings and ferrites on cables

Sensitivity analysis of the performance of thin absorbing coatings and ferrite chokes on cables to the variation in dielectric and magnetic properties of materials is carried out. This variation corresponds to possible uncertainty in measuring complex permittivity and permeability of materials. The analysis in this paper is done numerically using the 2D-FEM code. The modeled parameters are input impedance and EMI radiation reduction when applying absorbing materials and ferrite chokes on the cables, represented as monopole antenna rods. The material parameters of absorbing materials and ferrites used in this study were measured using the standard 7-mm coaxial air line. Higher sensitivity of the modeled parameters to the uncertainty of measuring complex permeability of absorbing materials and ferrites, and lower to the uncertainty of measuring complex permittivity, even in the case of high-permittivity absorbing coatings, have been demonstrated.