What are the working principles of ferrite absorbing materials?

1、 Working principle of ferrite absorbing materials

Ferrite absorbing materialBeing both a magnetic medium with magnetic absorption and a dielectric with electrical absorption is an excellent type of absorbing material.

In the low frequency range, the losses caused by hysteresis effect, eddy current effect, and magnetic aftereffect mainly result in the loss of ferrite to electromagnetic waves; In the high frequency range, the losses of ferrite to electromagnetic waves mainly come from natural resonance losses, domain wall resonance losses, and dielectric losses.

The mechanism of residual loss of absorbing materials varies in different frequency ranges due to different mechanisms of magnetization relaxation processes. In low-frequency weak fields, the residual losses are mainly magnetic aftereffect losses. At high frequencies, size resonance loss, domain wall resonance loss, and natural resonance loss all belong to the category of residual losses.

In summary, to obtain high loss ferrite absorbents, the methods include: increasing the saturation magnetization of ferromagnetic materials; Increase impedance coefficient; Reduce magnetic crystal anisotropy field; Since the resonance frequency is proportional to the magnetic crystal anisotropy field, it is possible to control the absorption band of the material by changing the magnetic crystal anisotropy field of the ferromagnetic material. In the actual preparation process, it can be controlled by changing the composition of the material and the preparation process.

2、 Application of Ferrite Sheet

In handheld devices such as payment phones, the main function of electronic tags is to reduce the absorption of signal magnetic fields by metal materials, and effectively increase the sensing distance by increasing the magnetic field strength The payment method for NFC mobile phones is through 13.56MHz; Implemented by RFID wireless radio frequency identification system. The RFID smart tag of this application is attached to the back cover of the phone, which can save space to a certain extent. In handheld electronic devices such as mobile phones, electronic tags need to be integrated or attached to the electronic device as a component to function. However, due to limited space, it is inevitable to attach RFID tags (usually passive) to the surface of conductive objects such as metals or to areas with metal components nearby. In this way, the alternating electromagnetic field induced by the signal emitted by the card reader can easily be attenuated by the eddy current of the metal, greatly reducing the signal strength and leading to the failure of the reading process. Therefore, in order to better apply card reading in the product, it is necessary to addAbsorberFerrite sheets have begun to be widely used in small payment mobile phones and RF fields.

Shielding boxes also require the use of ferrite as a shielding material in some low-frequency bands, and the overall application of ferrite is still very extensive.