Shielding effectiveness : Measurement methods and theoretical issues

The basic principles of Shielding Effectiveness (S.E.(dB)) in terms of Reflection Loss (R(dB)), Absorption Loss (A(dB)) and Round-Trip Reflections (B(dB)) including Maxwell’s laws and the equivalent Transmission Line – model are treated. Some typical examples for the S.E.(dB) are analyzed for different shielding materials. The influence of the wave-impedance ZW is indicated for the reflection loss in near- and far-field. The transfer-impedance of coaxial cables is determined and compared for different cable types. Measurement methods for S.E. (dB) such as the 2 chamber method, the Takeda-Riken method for near-field and the double Crawford-TEM-cell are discussed. Finally research results for modelling (FLO-EMC) of S.E. (dB) are compared with measurement results for the shielding effectiveness of a box containing an electronic board, where the metal box has an open front, a letterbox-front with a vertical or horizontal opening and 4, 8, or 81 open slots, where a fair match was found between the simulations and the experimental results.status: publishe