What are the classifications of absorbent materials? The following small editor for you to answer: microwave darkroom using the absorption body often made into a sharp split shape (golden tower shape), mainly by polyurethane foam type, non-woven non-combustible type, silicate plate gold film assembly type.
With the reduction of frequency (wavelength growth), the length of the absorption body is also greatly increased, the ordinary sharp split absorption body is similar to the relationship L/≈1, so at 100MHz, the sharp split length of up to 3000mm, not only in the process is difficult to achieve, but also microwave darkroom effective free space is greatly reduced.
Double or multi-layer flat
This absorbent can operate over a wide working frequency range and can be made into any shape. For example, the Japanese NEC company will be iron oxygen and metal short fibers evenly dispersed in the appropriate organic polymer resin into composite materials, the working band can be widened by 40% to 50%. The disadvantages are large thickness, complex process and high cost.
Only coating-type absorption materials can be used on the surface of the aircraft, and for the spread of the frequency band, the coating of composite materials is generally used. Such as lithium cadmium ferride coating thickness of 2.5mm to 5mm, in the cm band, can attenuate 8.5dB; When the thickness of the crystal ferrite coating is 2.5mm, it can attenuate 24dB at 9GHz. When the thickness of the ferride-coated neoprene coating is 1.7mm to 2.5mm, the attenuation of 5GHz to 10GHz is about 30dB.
High-performance absorbent material
Mixing the absorbent material into the engineering plastic makes it have both absorption characteristics and load capacity, which is a direction of the development of the absorbent material. Today, in order to further improve the performance of absorbent materials, foreign countries have also developed several shape combinations of complex absorbents.