Surge impedance of nonlinear coaxial line using ferrite beads

A ferrite sharpener is a nonlinear coaxial line using ferrite beads, which produces high-voltage, high-dV/dt pulses. Although the surge impedance of sharpener in the region where the ferrite is generally considered to be saturated is very important in practical applications, surge impedance and relative permeability in the region have not been clarified so far. Therefore, using three evaluation methods, we attempted to clarify the surge impedance and relative permeability of the ferrite sharpener in the region where the ferrite is generally considered to be saturated when the following parameters are changed: (1) magnetic field bias and (2) terminating resistance. We confirmed that different values of surge impedance and relative permeability were obtained in the experiments using the three evaluation methods. Also, we found that the simulation could reproduce a tendency similar to the experimental results.