Highly Integrated 3D-Radar System at 240GHz

• Applicants: Professor Dr.-Ing. Ingmar Kallfass; Professor Dr.-Ing. Thomas Zwick
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2013 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 241714687

In addition to measuring accuracy and resolution, important factors as reliability, robustness, size and price determine the fields of application of sensors. Radar systems have the advantage to deliver good results, even under adverse conditions (e.g. smoke). Radar systems with two-dimensional angular resolution are mostly large and expensive. Apart from mechanical scanning with a highly focusing antenna, the angular resolution of an antenna array can be principally achieved by two methods: electronic scanning by changing the phase of the individual radiating elements or to electronically evaluate all directions simultaneously using digital beam-forming. In the first case, the available signal-to-noise ratio (SNR) is limited by the measurement period, since the different directions must be sequentially scanned. Besides the high hardware complexity, especially in a two-dimensional case, digital beam-forming needs huge computing power, which leads to higher costs and significantly larger power requirements.In this project, novel frequency-agile antenna arrays are examined in a hybrid 2D-antenna system. Here, the radar beam is pivoted in one dimension over the frequency and in the other dimension via a phase shift network. Together with optimized transceiver architectures, 3D millimeter wave radar sensors for environmental monitoring (indoor tracking or collision protection for autonomous vehicles in the industrial production area) are developed. Especially at high frequencies, radars with 2D antenna arrays are promising. The small wavelength (e.g. 1.25 mm at 240 GHz) allows integration of antenna arrays with several elements in compact modules. Additionally the small wavelength enables the implementation of passive phase controlling feed networks as the Butler matrix together with active components directly on GaAs and thus can lead to an optimization of the radar system's SNR. To exploit the frequency-agility of the antennas, highly broadband on-chip components are necessary, which poses a challenge on their implementation, due to the strong parasitic effects.Besides the range resolution the combination of FMCW radar with the novel frequency-agile phased array and its feeding with GaAs MMICs allows the direction of arrival (DoA) measurement in two dimensions. This compared to digital beam-forming leads to a more efficient trade-off between hardware complexity, SNR and measurement time. The integration of MMIC and antenna in a package represents a particular challenge because the state of the art waveguide packages (split-block) with their high suitability for heat dissipation can no longer be used. New concepts must be analyzed and optimized with high-performance RF interconnections to the antenna as well as good heat dissipation properties.

• DFG Programme: Research Grants