A Minkowski-like fractal composite metamaterial for S-C band radar and infrared compatible stealth

Due to the opposite stealth mechanisms of radar and infrared waves, and the lack of narrow-band absorption at a single frequency point in metamaterials, it is difficult for low-frequency broadband radar and infrared waves to be compatibly stealthy at thin thickness. In order to solve the problem, Minkowski-like fractal metamaterial with frequency-selective surface of "passing-low-frequency and blocking-high-frequency" property is designed. The multiscale property of Minkowski-like fractal constructs multiple absorption frequency points and its suitable iteration factor achieves broadband reconfiguration of the absorption frequency points, which enables broadband absorption in S and C bands. Besides, the magneto-electric dual loss mechanism brought by the fractal and the intrinsic loss of the medium are the most fundamental reasons for the stealth being caused. In addition, the selection of iterative cell with infrared emissivity below 0.3 and the self-similarity property of Minkowski-like fractal make the metamaterial embody excellent infrared stealth performance. Ultimately, the 2.24 mm thick fractal metamaterial achieves cross-band radar wave absorption in the range of 3.41-5.82 GHz while being compatible with infrared wave stealth. The layered fractal model provides a new design idea for broadband stealth under multi-band compatible stealth.