Annual Report 2021

In July, Dr. Sven Thomas, a member of the Bochum Research Group and the Chip Design Group of the Integrated Circuits and Sensor Systems Department, defended his doctoral thesis »System and antenna concepts for an FMCW radar system based on a 240 GHz SiGe transceiver MMIC«.    

After completing his master’s degree in electrical engineering and information technology at Ruhr-Universität Bochum (RUB), Prof. Dr.-Ing. Nils Pohl brought him to Fraunhofer FHR in 2013, where Dr. Thomas worked on chip and system development with higher frequencies (keyword 240-GHz radar) in the newly founded Chip Design group. This resulted in his dissertation, supervised by Prof. Pohl, which deals with the development of a compact and precise FMCW radar sensor that achieves a modulation bandwidth of 52 GHz in the frequency range around 240 GHz. The basis of this system is a SiGe transceiver MMIC developed in cooperation between RUB and Fraunhofer FHR, fabricated in Infineon’s B11HFC SiGe BiCMOS technology.     

By integrating any high-frequency components on the MMIC, including on-chip antennas, costly high-frequency PCBs can be eliminated. The result: a compact, cost-effective and robust design that can be used in confined spaces and harsh industrial environments. The wide FMCW modulation bandwidth enables high range resolution, ensuring high selectivity and image resolution even in complex measurement scenarios. »The core of my work relates to an unwanted effect of the sensor: The radar emits a 120 GHz signal at half the frequency in addition to the desired frequency at 240 GHz. This leads to false targets at half the range. To prevent this, I designed a frequency-filtering plate based on an interference filter that suppresses this half frequency. Then, this filter structure was integrated into the existing drop-shaped lens. Thus, I developed a frequency-filtering dielectric lens, for which a patent application has been filed,« explains Sven Thomas.

In early 2021, Dr. Iole Pisciottano successfully defended her PhD thesis entitled »Multidimensional Passive ISAR for Maritime Target Imaging«. The 37-year-old works in the Passive Radar and Anti-Jamming Techniques department, in the Passive Sensor Network group of Dr. Diego Cristallini, who was also the supervisor of her thesis. She received her PhD at the Sapienza University in Rome under Prof. Debora Pastina (Department of Information Technology, Electronics and Telecommunications).   

The PhD deals with novel ISAR (Inverse Synthetic Aperture Radar) approaches for passive maritime target imaging. Among the available illuminators of opportunity, her work focuses on digital video broadcasting signals such as DVB-T and DVB-S. The combined exploitation of DVB-T and DVB-S is extremely attractive for passive imaging purposes because they have complementary characteristics in terms of operating bandwidths, transmitter locations, and signals polarizations. Dr. Pisciottano developed ad hoc processing techniques to maximize the extracted information from the acquired ISAR products. In particular, she considered coherent and non-coherent multidimensional methods in terms of frequency, angle, and polarization, and validated them with experimental data from field trials.   

Dr. Pisciottano worked at the Institute for three years as principal investigator of the BMBF project »Radar Signal Processing for Determination of Biomass of Barley Ears in Stands« after graduating in Telecommunications Engineering from the University Federico II in Naples. After a break and the birth of her child, she came back in 2017. A PhD was the goal from the beginning. Due to the department’s good contacts to and thematic overlaps with Sapienza University, the choice fell on Rome. »The supervision from Fraunhofer FHR and the university went very well and I really appreciated the opportunity to work regularly on site in Rome. Unfortunately, the conclusion with the defense could only take place online due to corona – but that also worked out well,« says Dr. Pisciottano.