Simulation and Measurement Based Study of the Asymptotic Low-Frequency Electric and Magnetic Shielding Effectiveness for Board Level Applications

In this article, the application of different types of sources to characterize board level electric and magnetic shielding effectiveness (SE) within the frequency range of 10 MHz-10 GHz is investigated. Our primary focus is on characterizing practical SE values for board level shields (BLSs) using the SAE ARP 6248 stripline method, which was originally designed for on-board gaskets. Various on-board sources and the corresponding SE of a BLS are elucidated to gauge their performance in the near-field region, particularly considering the close proximity between the shields and on-board sources. Our investigation integrates both 3-D modeling using the finite-difference-time-domain solver and measurements. In addition, the shielding performance of a BLS based on total radiated power (TRP) is studied in 3-D modeling to provide a comparison with the stripline method. It is shown that there is a correlation between wave impedance and SE of BLSs, which helps discern the nature of the on-board sources, i.e., asymptotic behavior of electric and magnetic sources. Notably, the numerical simulation study demonstrates a good level of agreement between the stripline method and the method based on TRP. Finally, validation through practical laboratory experiments using the stripline method confirms a significant alignment between the measured and simulated SE values.