Novel Planar Slow-Wave Structures for High-Power Broadband Millimeter and THz-band Traveling-Wave Tubes

• Applicant: Professor Dr.-Ing. Viktor Krozer, Ph.D.
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 430109039

Miniaturization and availability of vacuum electron devices could be the key point in millimeter-wave applications, such as radar, wireless and satellite communication. It therefore is necessary to find new fabrication methods of low-cost reliable vacuum electronic components that operate over 100 GHz, due to limitations of traditional manufacturing processes. The key driver here is the slow-wave structure (SWS) fabrication. The traditional SWS is difficult to manufacture due to its 3D character, its demands for micron precision at millimeter-waves for all three dimensions and at the same time due to large overall geometry of several centimeters. On the other hand, 2D planar structures can be realized by photolithographic techniques, which resolves the above limitations at the expense of high losses, narrow bandwidth and very low interaction in the travelling-wave tube. The objective of this proposal is to explore novel 2D structures, which could overcome the above limitations and pave the way towards efficient SWS manufacturing and travelling-wave realization at millimeter-wave frequencies. We propose to improve the state-of-the-art of the traveling-wave tubes, based on 2D SWS, both in terms of fabrication complexity and in terms of performances. In particular, this project aims to provide a novel solution for a high power TWT amplifier, operating at G-band around 220 GHz with more than 10 GHz bandwidth. This amplifier will necessitate studies on novel 2D planar SWS as an alternative to the narrow bandwidth Meander lines. It will explore metamaterial based planar structures, considering both single and multilayer substrates. Photolithographic techniques will enable reliable fabrication of such SWS with high precision and repeatability. Theoretical and simulation studies will be performed on these SWS structures with the aim of bandwidth and coupling impedance optimization. Experimental characterization of these structures will validate the simulations. The success of the project is based on a strong collaboration and synergy between the two groups.The two groups will use complementary design approaches and different electromagnetic simulators. They will exchange the results and design models of the studied architectures and will systematically evaluate the structures for their performance capabilities. The two groups will also fabricate the SWS devices using different fabrication approaches and exchange the fabricated devices for experimental evaluation. In particular, GUF will be in charge of the fabrication of single and multilayer SWS structures with standard optical lithography, while Saratov team will realize the SWS devices through laser machining.A preliminary collaborative study has been performed already by the two groups and the results will be presented at the international conference on vacuum electronics IVEC 2019.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Foundation for Basic Research, until 3/2022
• Cooperation Partner: Professor Nikita M. Ryskin, Ph.D., until 3/2022