A Mathematical Model of Magnetic Ring Based on High Frequency Characteristics

Ferrite magnetic rings have excellent performance in suppressing high frequencies, making them widely used in anti-interference. Based on the cylindrical coordinate system and considering the skin effect at high frequencies, this paper describes the internal electromagnetic field environment of the magnetic ring sleeved on the guide rod from Maxwell equation. It is theoretically deduced that the permeability of the magnetic ring is no longer a real number at high frequencies, but a complex form. The explicit expression of the real part and the imaginary part of the permeability is obtained, revealing the reason for the phase deviation of the magnetic field strength and magnetic flux density inside the magnetic ring. Combined with Faraday’s electromagnetic induction principle, it is obtained that the magnetic ring will produce Counter-electromotive force on the guide rod, and then the effect of the magnetic ring on the guide rod can be equivalent to the parallel connection of resistance and inductance, where the resistance corresponds to the loss characteristics of the magnetic ring, and the inductance corresponds to the energy storage characteristics of the magnetic ring, revealing the internal electromagnetic field characteristics of the magnetic ring at high frequencies and establishing the mathematical model of the magnetic ring at high frequencies.