A conformal coding metasurface for dual polarization conversion and radar cross section (RCS) reduction

Integrated meta-devices are the need of modern stealth application systems and have recently received a great deal of attention. Most studies have concentrated on the physics and structural design of planar metasurfaces, while conformal design that is suitable for arbitrarily curved surfaces has been rarely discussed. In this study, a conformal polarization-independent 1-bit coding metasurface (CM) is proposed. A fundamental element of a proposed CM is firstly designed which converts the linearly polarized incident electromagnetic wave into its orthogonal equivalent at 8.53-11.63 and 18.67-22.34 GHz with a polarization-conversion-ratio of more than 90%, and enables linear-to-circular polarization conversion from 12.40 to 17.56 GHz. Next, the basic element is rotated by 90 degrees to generate another element with a phase difference of pi between them. Both these elements are distributed in an array using a random aperiodic coding sequence to form 1-bit CM for radar cross section (RCS) reduction. More than 10 dB RCS reduction for arbitrarily polarized waves has been realized in dual frequency bands ranging 8.75-11.22 and 19.10-21.20 GHz, for planar as well as with conformal structures. A prototype is fabricated, and the experiments show a good agreement with simulated results. Potential applications of the proposed design include reflector antennas, radar, satellite communication, and stealth technology.