Ferrite is a ferrimagnetic metal oxide. In terms of electrical properties, the resistivity of ferrite is much larger than that of elemental metal or alloy magnetic materials, and it also has higher dielectric properties. The magnetic properties of ferrites also show that they have high permeability at high frequencies. Therefore, ferrite has become a non-metallic magnetic material widely used in the field of high frequency weak current. Due to the low magnetic energy stored in the unit volume of ferrite, the saturation magnetic induction (Bs) is also low (usually only 1/3~1/5 of pure iron), which limits its use in low frequencies requiring higher magnetic energy density.