Correspondence of Frequency Dispersion of Primary Parameters of Shielded-Printed Circuit Board to Shielding Effectiveness of Near Magnetic Field

In this paper, correspondence of the frequency dispersion of the primary parameters when thin conductive shield is mounted near the differential paired lines to the shielding effectiveness (SE) for the near magnetic field is investigated. The frequency dispersion and SE for the near magnetic field are evaluated by using electromagnetic simulation and measurements. The measured results and simulated results of SE for the near magnetic field are in good agreement. It is demonstrated that the frequency dispersion appeared in the frequency band where the near magnetic field SE is smaller than 20 dB. In addition, it is demonstrated that the frequency band that frequency dispersion occurs changes depending on the difference in electromagnetic field coupling.