Active rader cross section signature management with metasurfaces

在这个项目中，我们将开发用于减少和总体上管理复杂物体的雷达横截面（RCS）的技术，以加强对飞机和无人机的监视，以实现安全和安全目的。其基本原理将基于通过工程表面（超表面）主动消除电磁场。现有的“隐身”技术依赖于散射重新定向（通过车辆几何形状的设计）和雷达吸收材料（RAM）的组合，与之相比，该方法具有潜在的显著优势。特别是，雷达信号重定向可以通过使用多静态雷达来检测，也就是说，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吸收入射雷达信号，从而产生可探测的红外信号。此外，需要较厚的RAM来有效地吸收广谱的频率并具有足够的衰减。相反，在这个项目中，我们试图减少物体周围各个方向的散射波，但不吸收它。这就是所谓的“隐形”，与传统的“隐形”方法形成对比。此外，与其他所谓的超材料斗篷相比，这种主动隐形方法有可能导致非常薄的斗篷，与被隐藏的物体共形，可以掩盖大型物体。然而，为了使这项技术在实际应用中可行，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，例如减少飞机和无人机的雷达横截面（RCS）。

In this project we will develop technology for the reduction and in general the management of the radar crosssection (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.