Tunable Stealth Metasurface via Dual Geometric Phase Modulation

Tunable metasurfaces are verified as an effective way to modulate electromagnetic (EM) waves within a thin interface. However, most tunable metasurfaces currently use electronic control methods, making it difficult to achieve large-scale sample manufacturing. This article proposes a novel metasurface design approach based on germanium telluride (GeTe) film, which is used to achieve anomalous scattering of radar detection signals. By designing the composite units to form a 2-bit dual geometric phase modulation coding array, low reflection characteristics in different frequency bands can be achieved by controlling the state of GeTe, which adds a new degree of freedom to array design. In this article, the phase characteristics of composite units and the EM scattering characteristics of different array arrangements are analyzed in detail. The simulation and experimental results indicate the designed metasurface has excellent dual geometric phase independent modulation ability, and the reflectivity reduction of the fabricated sample is less than -10 dB in the range of 11.6-15.2 GHz and 8.0-11.6 GHz before and after phase transition of GeTe film, respectively. This method has significant advantages in design, fabrication, and modulation, which determine that this research can be a good candidate for military stealth materials. The 2-bit coding units are designed by integrating germanium telluride, and electromagnetic characteristics of the arrays under different arrangements modes are analyzed, achieving abnormal scattering of radar detection signals in the Ku and X bands. This method realizes double geometric phase modulation function, which adds new design freedom and can become a good candidate for stealth materials.image