About absorbing material, let's have a look at Baidu Encyclopedia's Description: the so-called absorbing material refers to a kind of material that can absorb or greatly reduce the electromagnetic wave energy projected on its surface, so as to reduce the interference of electromagnetic wave. In engineering application, in addition to high absorption rate of electromagnetic wave in a wide frequency band, it is also required to have the properties of light weight, temperature resistance, humidity resistance and corrosion resistance.
According to the loss mechanism, the absorbing materials can be roughly divided into the following three categories:
1) Resistance type loss
This kind of absorption mechanism is related to the electrical conductivity of the material, that is, the higher the conductivity, the greater the macro current caused by carriers (including the current caused by the change of electric field and eddy current caused by the change of magnetic field), which is conducive to the conversion of electromagnetic energy into heat energy.
2) Dielectric loss
It is a kind of dielectric loss absorption mechanism related to the electrode, that is, the electromagnetic energy is converted into thermal energy consumption and dissipated through the "friction" effect produced by the repeated polarization of the medium. The process of dielectric polarization includes: electron cloud displacement polarization, polar medium electric moment turning polarization, ferroelectric domain turning polarization and wall displacement.
3) Magnetic loss
This kind of absorption mechanism is a kind of magnetic loss related to the dynamic magnetization process of ferromagnetic medium. This kind of loss can be subdivided into: hysteresis loss, gyromagnetic eddy current, damping loss and magnetic aftereffect effect effect. Its main sources are domain turn, domain wall displacement and domain natural resonance, which are similar to the hysteresis mechanism.
Design principle of absorbing materials
1) Nano materials, planar hexagonal ferrite, amorphous magnetic fiber, granular film and other high-performance absorbers are used as absorption medium;
2) Using the new absorption principle electromagnetic resonance and eddy current loss, the microwave absorbing materials are thin in thickness, light in weight, wide in absorption band and high in absorption rate;
3) According to Maxwell equation, genetic algorithm (GA) is used to realize the simulation (CAD) of electromagnetic wave absorbing materials, which can maximize the absorption medium characteristics and shorten the development cycle of materials, so as to meet the special needs of users.
Applications related to absorbing materials:
1) It can suppress electromagnetic interference, improve antenna pattern and improve the accuracy of radar direction finding and ranging;
2) Prevent electromagnetic interference, electromagnetic wave radiation and waveform shaping of microwave devices and equipment;
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