Research On Metasurfaces And Their Application In Stealth

Due to the development of radar detection technique, traditional stealth methods are unable to meet military demands. Therefore, it is necessary to make a revolution to stealth technology. Metasurfaces are the two-dimensional(2D) equivalent of metamaterials. By tailoring the structure and arrangement of sub-wavelength unit cells, metasurfaces are capable of controlling electromagnetic waves freely and effectively, which provides a new way of thinking for radar stealth. It can be shown that stealth method based on metasurfaces has considerable advantages over traditional methods owing to its features of simple realization, compact structure, low loss and easy fabrication. In this thesis, metasurfaces and their application in stealth have been investigated. The main contexts and contributions are shown as follows:With two kinds of artificial magnetic conductors(AMCs), a chessboard metasurface for stealth working in X band is constructed. Due to destructive interference, the backward radar cross section(RCS) of a metal plate covered by this metasurface can be reduced significantly. Full wave simulation is executed to show its performance.Referring to microstrip reflectarray antennas, a metasurface for RCS reduction is designed, which can redistribute the scattering energy toward various directions. Full wave simulations show that the backward scattering of a metal plate covered by this metasurface can be reduced significantly in the whole X band.An unit cell with wideband linear polarization conversion property is designed and analyzed. By tailoring the open angle and rotation angle of the unit cell, the phase and amplitude of cross-polarized reflection can be separately manipulated. Combining the concepts of random metasurfaces and coding metamaterials, a novel metasurface for RCS reduction is proposed. The metasurface is capable of rotating a linearly polarization to its orthogonal one and realizing diffuse reflection, both of which are benefit to improve the stealth performance and extend the operating bandwidth. Simulations and experiments verify the excellent stealth characteristics.