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

• Final Report Year: 2025

Final Report Abstract

The objective of this project was to develop innovative concepts and methods for additively manufactured, integrable, electrically controllable dielectric image guide components, and to demonstrate their feasibility through individual components and a fully printed phase-controlled antenna in the W-band. The construction of these components involved a closed, sealed cavity into which LC could be introduced, the investigation of how electrodes can be integrated into the component, and the combination of various manufacturing processes to ensure fully additive fabrication. In the initial project phase, adhesion between the dielectric and metallic substrate could be achieved through plasma treatment, inherently promising a reduction in insertion loss of approximately 3 dB compared to glued, conventionally milled Rexolite DILs. Building upon this, cavities could be generated in the transmission line elements, which reliably accommodate LC, thereby enabling the realization of phase shifters. However, these exhibited higher insertion losses compared to glued, conventionally milled controllable Rexolite components due to significant variations in cavity geometry and the associated losses. Furthermore, noncontrollable leaky-wave antennas were fabricated using a combination of polymer extrusion and piezo-jetting of conductive silver nanoparticle ink and were electrically characterized. In the field of system integration, low-reflection interfaces, i.e., mode converters from standard planar stripline technology to dielectric image line, were successfully implemented. However, with increasing structural complexity, it was not possible to realize group antennas controllable with LC-based phase shifters. Nonetheless, it was demonstrated that individual components based on DIL, such as transmission lines, transitions, antenna elements, and electrically controllable phase shifters, can be reliably fabricated in this manner, laying the foundation for a DIL-based packaging and interconnection technology for applications in the triple-digit GHz range. It should be emphasized that the insights gained from this study have also been incorporated into other research projects.

Publications

• Dielectric Image Line Liquid Crystal Phase Shifter at W-Band. In: 2020 German Microwave Conference (GeMiC). 2020, S. 156–159
  Henning Tesmer & a.
  
• Liquid Crystal Based Parallel-Polarized Dielectric Image Guide Phase Shifter at W-Band. 2020 IEEE/MTT-S International Microwave Symposium (IMS), 305-308. IEEE.
  Tesmer, Henning; Reese, Roland; Polat, Ersin; Jakoby, Rolf & Maune, Holger
  
• Feasibility of Additively Manufactured Tunable Liquid Crystal Loaded Dielectric Waveguides. IEEE Microwave and Wireless Components Letters, 31(8), 973-976.
  Tesmer, Henning; Gold, Gerald; Bachbauer, Felix; Polat, Ersin; Sippel, Mark; Jakoby, Rolf; Vossiek, Martin & Maune, Holger
  
• Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications. Crystals, 11(1), 63.
  Tesmer, Henning; Razzouk, Rani; Polat, Ersin; Wang, Dongwei; Jakoby, Rolf & Maune, Holger
  
• Dielectric Image Line Rod Antenna Array With Integrated Power Divider at W-Band. 2022 16th European Conference on Antennas and Propagation (EuCAP), 1–5.
  Tesmer, Henning; Stumpf, Daniel; Polat, Ersin; Wang, Dongwei & Jakoby, Rolf
  
• Fully-Integrated Dielectric Image Line Phased Array with Liquid Crystal Phase Shifters at W-Band. 2022 52nd European Microwave Conference (EuMC), 171-174. IEEE.
  Tesmer, Henning; Polat, Ersin; Wang, Dongwei & Jakoby, Rolf
  
• Reconfigurable Liquid Crystal Dielectric Image Line Leaky Wave Antenna at W-Band. IEEE Journal of Microwaves, 2(3), 480-489.
  Tesmer, Henning; Razzouk, Rani; Polat, Ersin; Wang, Dongwei & Jakoby, Rolf
  
• Feasibility of Manufacturing Dielectric Image Lines by Using Laser-Based Directed Energy Deposition of Polymers. IEEE Access, 11, 120585-120592.
  Wittmann, Alexander; Bader, Tobias; Chamandani, Saeed Alidoust; Hentschel, Oliver; Schmidt, Michael & Gold, Gerald
  
• Liquid Crystal Dielectric Image Lines for Integrated Reconfigurable Millimeter-Wave Beamsteering Applications. Diss.
  Henning Tesmer
  
• 3D-Printed Dielectric Image Lines Towards Chip-to-Chip Interconnects for subTHz-Applications. 2024 IEEE International Conference on Microwaves, Communications, Antennas, Biomedical Engineering and Electronic Systems (COMCAS), 1-5. IEEE.
  Hahn, Leonhard; Pfahler, Tim; Bader, Tobias; Gold, Gerald; Vossiek, Martin & Carlowitz, Christian
  
• Additively Manufactured Leaky Wave Antenna in Dielectric Image Line Technology. 2024 54th European Microwave Conference (EuMC), 224-227. IEEE.
  Bader, Tobias & Gold, Gerald
  
• Tight Non-Radiating Bends of 3D-Printed Dielectric Image Lines Based on Electromagnetic Bandgap Mirrors. 2024 IEEE Wireless and Microwave Technology Conference (WAMICON), 1-4. IEEE.
  Hahn, Leonhard; Bader, Tobias; Carlowitz, Christian; Vossiek, Martin & Gold, Gerald
  
• Towards Dielectric Chip-to-Chip Interconnects for THz Applications. 2024 IEEE Wireless and Microwave Technology Conference (WAMICON), 1-4. IEEE.
  Bader, Tobias & Gold, Gerald
  
• Analog Phase Shifter with Substrate Integrated Electrodes in Dielectric Image Line Technology. 2025 55th European Microwave Conference (EuMC), 270-273. IEEE.
  Bader, Tobias & Gold, Gerald