Additive manufacturing of dielectric phased array antennas with liquid crystal beam-steering for future integrated millimeter wave systems

在w波段和更高频率下，可调谐平面射频元件由于其高损耗而不能再合理使用。因此，在之前的研究项目中，已经为基于介质成像线（DIL）填充特殊微波液晶（lc）的新型、低损耗、可调谐射频元件奠定了基础。最初的相移测试结构证明了功能原理，但由于它们是单独铣削的，并且具有开腔，因此很难将其集成到更大的系统中。闭合这些lc基介电元件的空腔反过来又需要粘合剂，这会导致额外的损失。伴随着粘附问题，有时甚至会因LC泄漏而导致故障，使得这种介电技术难以更广泛、更可靠地使用。另一方面，创新的增材制造方法通过将介电材料直接打印到金属接地板上，消除了麻烦的气隙，并且不需要将它们粘在金属接地板上或密封所产生的LC腔。此外，该方法允许在DIL顶部进行金属化结构的后续图案，用于控制电极以定向液晶。因此，在这个有针对性的研究项目范围内，将分别创建、开发基于DIL拓扑的毫米波范围内增材制造、可积、电可调谐元件的基本原理、创新概念和方法。以单个元件和w波段完整的介质相控阵天线为例，说明了创新增材制造方法的研究和测试。一个目标是通过使用这种新的制造方法来证明可调谐DIL组件的可行性，探索射频组件增材制造的当前局限性，以及开发适当和专用的设计方法。所获得的知识将用于确保未来可靠的制造和设计规则。在此背景下，计划完成以下任务：1.)研究印刷的、不可调谐的天线元件，但它们已经与LC集成兼容；2.)将这一过程扩展到LC腔的封闭介质反射线的生产；3.)探索直接应用于印刷介质反射线的集成电极结构。最后，在介质镜像线拓扑结构下，对全印刷可操纵相控阵天线进行了分析和测试。

In the W-band and at higher frequencies, tunable planar RF components can no longer be used reasonably due to their high losses. In the previous research project the foundation was therefore already been laid for novel, low-loss, tunable RF components based on dielectric image lines (DIL) filled with special microwave liquid crystals (LCs). Initial phase-shifting test structures demonstrate the functional principle, but since they are individually milled and have open cavities, their integration into larger system turns out to be difficult. Closure of the cavities of these LC-based dielectric components in turn requires adhesive, which causes additional losses. Accompanied with adhesion problems that sometimes even lead to failures due to LC leakage, making broader and reliable usage of this dielectric technology difficult.Innovative additive manufacturing methods, on the other hand, eliminate troublesome air gaps by printing the dielectric material directly onto a metallic ground plate and do not require lossy adhesives to stick them to the metallic ground plate or to seal the resulting LC cavity. In addition, this method allows subsequent patterning of metallized structures on top of the DIL for the controlling electrodes to orient the liquid crystals.Therefore, within the scope of this targeted research project, basic principles, innovative concepts and methods for additively manufactured, integrable, electrically tunable components based on DIL topology in the millimeter-wave range are to be created, respectively developed. The research and testing of innovative additive manufacturing methods is exemplified by individual components and a complete dielectric phased array antenna in the W-band, consisting of the individual antenna elements, liquid crystal phase shifters and a feed network. One goal is to demonstrate the feasibility of tunable DIL components by using this new fabrication method, to explore the current limitations of additive manufacturing of RF components as well as to develop appropriate and dedicated design methods. The knowledge gained will be used to ensure future reliable manufacturing and design rules. In this context, the following tasks are planned: 1.) the investigation of printed, non-tunable antenna elements, which are, however, already compatible with LC integration and 2.) the extension of this process to the production of closed dielectric mirror lines with LC cavity as well as 3.) the exploration of integrated electrode structures, which are directly applied to the printed dielectric mirror line. Finally, 4.) the analysis and testing of a fully printed steerable phased-array antenna will be carried out in a dielectric mirror line topology.