Tunable Gradient-Index Fishnet for Beam Steering Applications at 60 GHz

现代通信系统需要具有可操纵辐射方向的天线。这样，移动通信伙伴就可以通过将天线重定向到移动伙伴而始终获得最佳信号。机械天线转向不可靠且成本高。因此，电子转向是首选。本课题将开发一种实现电定向天线的新方法。为此，液晶（LC）材料，因为它是已知的LC显示器将被用作可调材料。它将与超材料结构相结合。超材料是具有任意可定制材料特性的人工周期性结构。它们的性能甚至可以超越天然材料的材料性能。通过LC和超材料的结合，有可能开发出轻量化的低轮廓结构，可以像透镜一样排列在普通天线前面。利用透镜特性的电子转向，可以根据需要控制天线辐射。这种结构的概念证明是在我们之前的项目中完成的。然而，波束导向只能在一维空间内实现，且扫描角度范围有限。因此，将开发一种新的结构，允许在二维和增加扫描范围的波束转向。此外，工作频率将提高到60 GHz，以供下一代WiFi设备使用。为此，需要对新的二维调谐概念进行广泛的研究。同样，对天线特性的时间依赖效应也必须加以研究。除了理论方面，还必须发展新的制造技术，以便将液体材料精确地密封在几个单独的薄层中。包括适当的电极为LC转向将被研究。

Modern communication systems need antennas with steerable radiation direction. With that, moving communication partners can always be provided with an optimal signal by redirecting the antenna to the mobile partner. Mechanical antenna steering is unreliable and cost intensive. Therefore, electronic steering is preferred. In this project, a new way of realizing electrically steerable antennas will be developed. For this purpose, liquid crystal (LC) material as it is known from LC displays will be used as tunable material. It will be combined with Metamaterial structures. Metamaterials are artificial periodic structures with arbitrarily tailorable material properties. Their properties can even go beyond material properties of natural materials. By the combination of LC and Metamaterials it is possible to develop lightweight low profile structures which can be arranged like a lens in front of a common antenna. Using the electrical steering of the lens properties, the antenna radiation can be steered as desired.The proof of concept of such structures was done in our previous project. However, the beam steering was only possible in one dimension and with limited scanning angle range. Therefore a new structure will be developed which allows beam steering in two dimensions and with increased scanning range. Furthermore, the frequency of operation will be increased to 60 GHz to be usable for next generations WiFi devices. To this end, extensive research needs to be done regarding the new two-dimensional tuning concept. Likewise, time dependent effects on the antenna characteristics have to be studied. Besides the theoretic aspects, new fabrication techniques have to be developed so that the liquid material can be precisely sealed in several separate thin layers. The inclusion of appropriate electrodes for the LC steering will be studied as well.