Modify the Injection Probe Equivalent Models by Considering the Shield Slot and Ferrite Permittivity Capacitors

Explicit and hybrid equivalent models of bulk current injection probe are reviewed, these models don’t take slot and ferrite dielectric constant capacitive effects into account, which cause the appearance of negative values in the real part of ferrite permeability spectra when extracting it from measured input impedance of the probe. In this paper, these capacitances are calculated using CST Electrostatic Solver, then its effect on the probe equivalent series impedance, voltage transfer ratio, and the core predicted permeability are evaluated. The evaluation shows that introducing these capacitances cancels the abnormal negative permeability resulting in the model, without affecting the model validation.