Radar waves are microwaves, which are electromagnetic waves with a wavelength of 1 to 10 4 mm. Radar detects targets by relying on the properties of metal objects to reflect microwaves . The function of the radar wave absorbing coating is to make the incident radar wave propagate in all directions and attenuate or transform into heat energy through loss.
Theoretically speaking, anti-radar wave stealth coatings can attenuate the directional reflection of radar waves in several ways, such as radar wave interference, radar wave absorption, and radar wave diffuse reflection.
The mechanism of the interference type is to divide the incident microwave into two parts, one part is reflected , and the other part is reflected from the bottom layer through the coating. If the parameters such as the surface conductivity of the coating, the attenuation , and the thickness of the coating are appropriate, the phases of the two waves are just opposite, and the amplitudes are roughly similar, then the effect of the entire incident wave will be eliminated by interference. For the technical requirements of broadband, when the wavelength varies in a wide range from millimeter wave to decimeter wave, it is very difficult to control the interference of the wave by the thickness of the coating.
The absorption type relies on the current hysteresis loss of induced scattering or high-frequency dielectric loss, and converts electromagnetic wave energy into heat energy to eliminate incident radar waves and achieve the purpose of stealth. This kind of coating is basically not limited by the direction, and has been widely researched and applied at home and abroad.
Another idea is to use the principle of diffuse reflection. For example, the coating is made of different thicknesses, the thickest part is twice the thinnest part, and the surface of the coating forms an uneven structure, so that most of the radar waves are reflected at angles different and no longer return to the radar receiver. The profile of the coating is wavy or zigzag.
