Comparative Study of Electric and Magnetic Losses in Shielding Materials for Far-Field and Near-Field Electromagnetic Interference Suppression

This paper studies the working mechanism and performance of two typical shielding materials in both far-field (FF) and near-field (NF) scenarios. The shielding effectiveness (SE) of the two shielding materials is, respectively, dominated by the electric and magnetic losses. The SE levels of the two shielding materials are firstly compared in the FF scenario. Then, from the theoretical wave impedance properties of the two materials, their performance in the NF is also predicted. Finally, they are applied in the NF of a dipole antenna for validation. The results demonstrate that the magnetic one will introduce lower loss and can thus enhance the forward gain of the antenna. This paper reveals that shielding materials with high magnetic loss are advantageous over those with high electric loss in many emerging areas, such as directional near-field interference suppression and high-gain antennas' designs.