  Lift-off of sensor affects the prediction of electromagnetic properties for
both ferrous and non-ferrous steel plates. In this paper, we developed a
strategy to address this issue for ferrous plates. With increased lift-off, the
phase of the measured impedance for steel plates reduces. Meanwhile, the
magnitude of the impedance signal decreases. Based on these facts, a phase
compensation algorithm is developed which corrects the phase change due to
lift-off considering the magnitude of the impedance signal. Further, a new
magnetic permeability prediction technique is presented, which has been
validated by analytical and measured results. With this new technique, the
error in permeability prediction is less than 2% within the range of lift-offs
tested.
