Dual-function flexible metasurface for absorption and polarization conversion and its application for radar cross section reduction

In this paper, a flexible metasurface with dual functions of absorption and polarization conversion is proposed and applied for radar cross section (RCS) reduction. The metasurface unit adopts a metallic-backed structure, and its width and thickness are approximately 0.62 and 0.24 times the free-space wavelength at the center working frequency, respectively. Different from the traditional metasurface, the resonators with low-frequency absorption and high-frequency polarization conversion are horizontally combined to achieve dual-function integration without the use of tunable elements. The structure adopts a flexible substrate, which is also suitable for conformal conditions. From 3.74 to 14.84 GHz, the metasurface has good impedance matching characteristics. The metasurface performs effective absorption and polarization conversion in the frequency bands of 3.78–6.34 GHz and 7.90–14.80 GHz, respectively. The absorption is mainly achieved through the ohmic loss of the lumped resistance, while the polarization conversion is performed through the electromagnetic resonance of the metallic structure. Then, the sample prototype is fabricated for demonstration, and the measurement result is well consistent with the simulation one. Furthermore, the checkerboard-arrangement array of the metasurface and its mirror unit can efficiently reduce the RCS over 7 dB in the range of 3.52–15.28 GHz. As expected, the proposed flexible metasurface can not only be used as an absorber/polarization converter but also be combined to realize broadband RCS reduction, which is of great significance for multi-function and conformal stealth applications.