Absorbing materials can be divided into two types: single frequency absorbing and wideband absorbing

With the development of microwave technology and the popularization of electronic products, electromagnetic interference (EMI) generated by electromagnetic waves has become an increasingly serious problem, following air pollution, water pollution, and noise pollution, while bringing great convenience to people's lives.

    AbsorberAs one of the effective means of protecting against electromagnetic interference, it is widely used in military and civilian fields. In the military field, absorbing materials have been used for the safety protection of large weapons such as airplanes and ships since the Second World War. With the rapid development of modern sensing technology and the increasing maturity of radar detection technology, stealth has become an important indicator in today's weapon design. Absorbing materials can reduce the strength of radar detection signals to a certain extent, achieving the effect of target stealth. In civilian use, absorbing materials can not only be used to manufacture protective clothing to protect the human body from electromagnetic radiation, but also in building materials in public places, greatly reducing electromagnetic radiation in densely populated areas.

Absorbing materials are widely used materials for electromagnetic wave absorption, isolation, and suppression. The principle is to adjust the electromagnetic properties of the material so that it can effectively absorb electromagnetic waves and convert them into thermal energy or other forms of energy to be emitted. Absorbing materials can be divided into single frequency absorbing andBroadband absorptionTwo types.

Single frequency absorbing materialUsually, electromagnetic barrier plates with a thickness of 1/4 to 1/2 of the wavelength are used, and a layer of conductive coating or other material with good electromagnetic properties is coated on the surface of the plate. When electromagnetic waves are incident on the board, due to impedance mismatch, some of the energy will be reflected, while the other part will penetrate into the board, and then be absorbed by the conductive coating and converted into thermal energy for dissipation.

Broadband absorbing materials require more complex structures and compositions. The most typical one is the "multi-layer absorbing material", which is composed of alternating layers of different materials, and the thickness and composition of each material are designed according to the required absorption frequency band and absorption depth. Multilayer absorbing materials typically use materials such as polyimide, fluororubber, graphite, etc. as substrates, and then adjust their electromagnetic properties by coating conductive coatings, adding various additives such as carbon black, spherical or rod-shaped iron, etc., to achieve broadband absorption effects.

In addition to single frequency absorption and Broadband absorbing materialIn addition, there are various other types of absorbing materials, such as metamaterials, dielectric plates, impedance layers, polymer absorbing materials, etc. These materials have different structures and design characteristics, suitable for different electromagnetic wave absorption requirements.