In this work, a lumped-parameter circuit model of injection probes for bulk current injection (BCI) is derived from probe input-impedance measurement. The model accounts for the effects related to ferrite magnetic-core losses and degradation of the magnetic permeability with frequency. Model assessment is achieved by comparing predictions of currents induced by BCI in the terminations of an electrically-long single-ended interconnection with direct measurements in a real BCI test applied to the same structure. The proposed model provides a precise description of the coupling between the probe and the wiring under test for frequencies up to 500 MHz