Estimation of Electric Parameters of Thin Electromagnetic Shielding Materials

Abstract

It is important to know the electric parameters of the shielding material for numerical analysis. The purpose of this report is to estimate electric parameters of thin shielding materials. Electromagnetic field in the vicinity of a horizontal multi-layered material with a magnetic dipole source is calculated numerically by a Sommerfeld integral. On the basis of this calculation, we develop a "shielding box" for measuring the shielding effectiveness (SE) with little error. We compare the magnetic SE measured with the shielding box with that obtained by calculation to evaluate this method. Because calculation results are in good agreement with measurement results, we confirm that we can measure magnetic SE of thin shielding materials with this system. Next, we propose a method to estimate unknown electric parameters of shielding materials by using the SE measurement system and the numerical calculation. The electric parameters are derived by iterating numerical calculations to fit with experimental results within 1dB error. We estimated the electric parameters of Al (aluminum) material. Fitted results are in good agreement with the well-known values, demonstrating the validity of the developed method.