The so-called absorbing material refers to a type of material that can absorb or greatly attenuate the electromagnetic wave energy projected on its surface, thereby reducing the interference of electromagnetic waves. In engineering applications, in addition to requiring high absorption of electromagnetic waves in a wide frequency band, the absorbing material is also required to have light weight, temperature resistance, humidity resistance, and corrosion resistance.
The principle of the absorbing material is based on the magnetic microwave absorber, which converts the electromagnetic waves emitted by electronic equipment into heat energy by means of insulation loss, magnetic loss and impedance loss to achieve the effect of reducing electromagnetic radiation. It has high permeability and wide selection of frequency bands. And other characteristics, and can be targeted for specific frequency band development.
The absorbing material has good absorption characteristics in the range of 10MHz~6GHz, which can avoid electromagnetic interference or leakage caused by secondary reflection. The products are mainly absorbing patch types, which can also be processed into various shapes according to customer needs. Absorbers can be used in electronic equipment cavities such as notebook computers, mobile phones, and communication cabinets.
The absorbing material has good electromagnetic wave absorption effect and wide absorption frequency. It can be customized according to the frequency band required by the customer. It is thin and cost-effective, and has a wide range of uses and applications.
01Classified by the loss mechanism of absorbing materials
1) Resistive loss, this kind of absorption mechanism is related to the resistive loss of the material's conductivity, that is, the greater the conductivity, the greater the macro current caused by carriers (including the current caused by the change of electric field and the eddy current caused by the change of magnetic field). Large, which is conducive to the conversion of electromagnetic energy into thermal energy.
2) Dielectric loss, which is a kind of dielectric loss absorption mechanism related to the electrode, that is, the electromagnetic energy is converted into thermal energy dissipation through the "friction" effect generated by the repeated polarization of the medium. The dielectric polarization process includes: electron cloud displacement polarization, polar dielectric moment turning polarization, electric ferrite domain turning polarization, and wall displacement.
3) Magnetic loss. This type of absorption mechanism is a type of magnetic loss related to the dynamic magnetization process of ferromagnetic media. This type of loss can be refined into: hysteresis loss, gyromagnetic eddy current, damping loss, and magnetic aftereffects, etc. , Its main source is the magnetic domain turning, magnetic domain wall displacement and natural resonance of the magnetic domain similar to the hysteresis mechanism. In addition, the latest microwave loss mechanism of nanomaterials is a hot spot in the analysis of absorbing materials today.
02According to the element classification of the absorbing material
1) Carbon-based absorbing materials, such as graphene, graphite, carbon black, carbon fiber, carbon nanotube;
2) Iron-based absorbing materials, such as ferrite, magnetic iron nanomaterials;
3). Ceramic absorbing materials, such as silicon carbide;
4), other types of materials, such as: conductive polymers, chiral materials (left-handed materials), plasma materials.