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

• Applicants: Dr.-Ing. Gerald Gold; Professor Dr.-Ing. Rolf Jakoby
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 398656024

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.

• DFG Programme: Research Grants