Microwave absorbing materials

Microwave absorbing materials refer to materials that can absorb microwaves and electromagnetic energy with minimal reflection and scattering. The basic principle is to convert microwave energy into other forms of motion energy through a certain physical mechanism, and convert it into thermal energy through the dissipation effect of this motion. All forms of lossy motion excited by microwaves can serve as absorption mechanisms, with common mechanisms including electrical induction, magnetic induction, electromagnetic induction, and electromagnetic scattering.

Main characteristics

1. High absorption rate: Microwave absorbing materials have a high energy absorption rate within a certain frequency range, which can effectively absorb electromagnetic waves, reduce electromagnetic wave radiation and interference, and improve system performance and efficiency.
2. Broadband: Microwave absorbing materials have broadband characteristics and can achieve absorption in different frequency bands. They are widely used in electronic devices, communication equipment, radar systems, aerospace and other fields.
3. Lightweight and flexible: Microwave absorbing materials have small volume, light weight, and good flexibility, and can be designed into various shapes and sizes according to specific requirements, making them very suitable for application in different devices and equipment.
4. Heat resistance and corrosion resistance: Microwave absorbing materials are usually manufactured using high temperature, high pressure, chemical synthesis and other processes, which have excellent heat resistance and corrosion resistance, and can be used for a long time in harsh environments.

Main types

1. Classified by application:

   • Coated microwave absorbing material: it is made by adding absorbent in a certain proportion to polymer solution or lotion such as resin and rubber by a specific process. Convenient construction, low cost, suitable for complex shaped objects.
   • Surface mount microwave absorbing materials: capable of achieving complex structural design, using surface mount materials such as rubber sheets, ceramic sheets, and plastic sheets, but not suitable for very complex shapes.
   • Structural microwave absorbing materials: made by adding absorbers to non-metallic composite materials as carriers. It can reduce the scattering of electromagnetic waves and withstand certain loads. It is lighter in weight than general metal materials and has certain strength and stiffness.

2. Classified by working principle:

   • Interference type microwave absorbing material: It mainly interferes with electromagnetic waves, and at the center frequency point, the incident electromagnetic waves and reflected electromagnetic waves have opposite phases (phase difference of 180 °) and cancel each other out. The characteristic of this type of material is a narrow frequency range, which can be used at high frequencies, and the material can be made thinner.
   • Absorption type microwave absorbing materials are divided into two categories: electrical loss type and magnetic loss type. Usually, electrical loss materials have a better absorption effect on high frequencies; Magnetic loss materials are more effective in absorbing low frequencies. If the two are combined, a wide frequency range absorbing material can be made.

Main components and preparation process

The main components of microwave absorbing materials are absorbents, followed by binders and related additives. The absorption performance of microwave absorbing materials mainly depends on the absorbent and its preparation process. Absorbents are the main base materials that absorb electromagnetic waves and are prepared through specific process technologies. Absorbents are usually in powder or fiber form, such as ferrite powder, carbonyl iron powder, various ultrafine metal powders, silicon carbide powder, silicon carbide fibers, carbon fibers, metal fibers, and organic polymer materials. New absorbents include composite ferrite, ultrafine metal particles, silicon carbide, organic polymer (functional polymer) nanomaterials, etc.

application area

Microwave absorbing materials have a wide range of applications in multiple fields, including:

1. Communication equipment: used for anti-interference and reducing electromagnetic wave radiation, improving equipment performance and stability.
2. Electronic devices: can be used as electromagnetic wave absorbing and shielding materials for circuit boards, electronic components, etc., to reduce electromagnetic interference and noise.
3. Radar systems and aerospace: Electromagnetic interference is a key factor in radar systems and aerospace, and is therefore widely used as electromagnetic wave stealth materials for aircraft, missiles, rockets, and other products.
4. Medical equipment: It can not only reduce the electromagnetic radiation received by the human body, but also be used to prevent electromagnetic interference in medical equipment, improve the stability and reliability of medical equipment.