Research On Metasurfaces With Abnormal Reflection Characteristics Of Electromagnetic Waves

The key of stealth technology is to reduce the Radar Cross Section (RCS) of the target itself. For the widely used monostatic radar technology, only the backscattering RCS contributes to the radar singles. With the development of all-round, multi-level and wide-band electromagnetic radar detection technology, it becomes more and more difficult for the conversional stealth technology to meet the demand of the stealth performance of the future weapons. Furthermore, the emerging electromagnetic metamaterial absorber is difficult to break through its intrinsic narrow bandwidth limitation. Therefore, exploration on new RCS reduction method has not only theoretical significance but also importance of practical applications.Metasurface is the two dimensional form of metamaterial, which is the recent hot research topic in the metamaterial community. In this thesis, research on abnormal reflection characteristics of metasurface has been carried out both theoretically and experimentally based on the Generalized Snell’s Law. Various kinds of unit cells has been designed and simulated to introduce different phase change on the incident interface. By reasonable arrangement of the unit cells we can tailor the wave-front of the reflected wave in an arbitrary way and eventually change the reflection direction and the scattering lobe shape, to reduce the backscattering reflection. The main contents and contributions of this thesis are summarized as follows:1.Abnormal reflection metasurface is designed to deflect the incident wave to any specific angle with the Generalized Snell’s Law as the basis. Both simulation analysis and experiment results show that the backscattering reduction is well achieved in the whole X-band, thus verify the effectiveness of the design. The proposed structure can be applied in areas such as antenna reflector array and stealth technology with excellent properties on cost, size, backscattering reduction performance and so on.2.Inspired by the concept of lambertian surface and diffuse optical phenomenon, we design a kind of random reflection metasurface which can’diffuse’the incident electromagnetic wave within a considerable bandwidth. The effectiveness of the design is verified by simulation and experiment, which show that random reflection and back scattering reduction is well achieved in X-band. With a thin structure, light weight, adjustable band, rich control capability and other properties, the random reflection metasurface has potential research and application prospects in the antenna radome, electromagnetic stealth fields.