A Multifunctional Coating for Radar-Infrared Stealth-Compatible at High Temperatures

In order to achieve compatibility stealth for the infrared radar, a multifunctional coating for achieving both radar stealth through polarization conversion and infrared emission reduction at high temperature was skillfully designed in this paper. The multifunctional coating consists of three layers, from outside to inside, followed by the metasurface, the high-temperature resistant dielectric and the metal background. The radar stealth at microwave frequency was mainly generated from polarization conversion excitation through the unsymmetrical metasurface structure. Infrared emission reduction is attributed to the reflection of the metasurface with a high filling ration. By the simulation, radar stealth with an efficiency of 90% could be achieved in the low-frequency band of 5.2-7.8 GHz, and the infrared emission of the multifunctional coating could be as low as 0.22. Furthermore, the experimental results at different temperatures demonstrated that the theoretical design is effective. The measured reflection in the 5-9 GHz frequency band is below -8 dB and lower as the frequency increases, indicating more than 84% polarization conversion is achieved. A low emission performance is also validated, with the mean emissivity as low as 0.25. Because of the excellent multispectral compatibility, the multifunctional coating may find applications in multispectral stealth technology.