The higher the permeability of ferrite PQ core, the greater the impedance of low frequency and the smaller the impedance of high frequency. We can choose different processes to make ferrite cores according to our own needs.

Ferrite PQ cores can generate different impedance at different frequencies, and the impedance of the cores increases dramatically as the signal frequency increases.

It doesn't require grounding like other filtering methods, so it doesn't have very specific requirements for this design for that reason. Another point is that the ferrite core is very convenient to use, directly on the need for filtering of the cable can be; The other thing is that when you use it as a common-mode choke, you don't distort the signal which is very valuable for a wire that's carrying a ferrite core at high frequencies.

The invention relates to a manufacturing method of multipole ferrite PQ magnetic core, in which a circular magnet with isotropic or anisotropic diameter direction is made by hot processing. The inner circumference of the ring magnet is polygon, the thickness of the ring wall changes periodically, and the number of poles of the ring magnet is equal to the number of periods. Compared with the prior art, it has the advantages of convenient assembly, accurate installation and positioning, and small tooth groove effect. Magnet demagnetization effect is small and hard to fall off under high temperature or high speed.