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

现代通信系统需要辐射方向可调的天线。这样，通过将天线重定向到移动伙伴，移动通信伙伴可以始终被提供最佳信号。机械式天线转向不可靠，成本高。因此，电动方向盘是首选。在本项目中，将开发一种实现电可控天线的新方法。为此，将使用从LC显示器已知的液晶(LC)材料作为可调谐材料。它将与超材料结构相结合。超材料是一种人工周期性结构，具有任意可裁剪的材料特性。它们的性质甚至可以超越天然材料的物质性质。通过将液晶和超材料相结合，可以开发出轻巧的低轮廓结构，这种结构可以像透镜一样布置在普通天线的前面。利用透镜的电转向特性，天线的辐射可以根据需要进行转向。这种结构的概念验证在我们之前的项目中已经完成了。然而，波束转向只能在一维空间中进行，且扫描角度范围有限。因此，将开发一种新的结构，允许在两个维度上进行波束控制，并具有更大的扫描范围。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，必须研究天线特性的随时间变化的影响。除了理论方面，还必须开发新的制造技术，以便液体材料可以精确地密封在几个单独的薄层中。还将研究用于LC转向的适当电极的包含。

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.