Active rader cross section signature management with metasurfaces

在这个项目中，我们将开发减少和管理复杂物体雷达截面积（RCS）的技术，以加强对飞机和无人机的监视，以实现安全和安保目的。基本原理将基于通过工程表面（超表面）主动消除电磁场。与现有的“隐身”技术相比，这种技术依赖于散射重定向（通过设计飞行器的几何形状）和雷达吸收材料（RAM）的组合，所提出的方法提供了显着的优势。特别地，可以通过使用多基地雷达来检测雷达信号重定向，即，通过使用车辆周围的接收器而不仅仅是寻找镜面反射。另一方面，RAM吸收入射的雷达信号，从而产生可检测的红外特征。还需要厚RAM以有效地吸收宽频谱的频率并具有足够的衰减。与此相反，在这个项目中，我们试图减少散射波在所有方向上的对象，但不吸收它。这是什么可以被称为“隐身”，以对比它与传统的“隐身”的方法。此外，与其他所谓的超材料隐身相比，这种主动隐身方法有可能导致非常薄的隐身，这些隐身与要隐藏的物体共形，并且可以掩盖大型物体。然而，为了使这项技术在现实世界中的应用可行，必须克服重大挑战。因此，该项目的目的是开发和演示关键里程碑，以实现使该技术在实际应用中可行的目标，例如飞机和无人机的雷达截面（RCS）减小。

In this project we will develop technology for the reduction and in general the management of the radar cross**section (RCS) of complex objects in order to enhance the surveillance of aircrafts and drones for security and safety purposes. The basic principle will be based on the active cancellation of the electromagnetic fields by means of engineered surfaces (metasurfaces). Compared to existing "stealth" technologies that rely on a combination of scattering re-direction (through the design of the geometry of the vehicle) and radar absorptive materials (RAM), the proposed approach offers the **potential for significant advantages. In particular, radar signal redirection can be detected by the use of multi-static radar, that is, by using receivers surrounding the vehicle and not just looking for specular reflections. On the other hand, RAM absorbs the incident radar signal thus producing a detectable infrared signature. Also thick RAM is needed to effectively absorb a broad spectrum of frequencies and with enough attenuation. In contrast, in this project we seek to reduce the scattering waves in all directions around the object but without absorbing it. This is what can be termed as "cloaking" to contrast it to the conventional "stealth" approach. Furthermore, in contrast to other so-called metamaterial cloaks, this active cloaking approach has the potential to lead to very thin cloaks that are conformal to the objects to be concealed and can cloak large objects. However, significant challenges have to be overcome in order to make this technology viable for real-world applications. Therefore, the purpose of this project is to develop and demonstrate key milestones toward the goal of rendering this technology feasible forpractical applications, such as for the radar cross section (RCS) reduction of aircraft and drones.**