Project S01 - Beamforming Concepts for THz Frequencies

Principal Investigators: Prof. Dr. Andreas Czylwik, Dr. Lars Häring, UDE NTS

Most applications of the MARIE project require highest carrier frequencies up to the THz frequency range. According to the Friis transmission equation, the received power in a radio system decreases with increasing carrier frequency. Therefore, in the MARIE project antennas with high gain have to be utilized. This is true for radar systems as well as for communication systems at highest carrier frequencies. Furthermore, antennas need to be adjusted in specific directions in order to scan a surface or volume. This may be done by steering high gain directional antennas mechanically into the desired directions. However, mechanical steering has the disadvantage that the direction adjustment response time is long because of mechanical inertia. Furthermore, in most cases electromechanical drives consume a significant amount of energy.

The solution of this problem is based on well-known methods of electronic beamforming, also including approaches with MEMS (micro-electromechanical system) actuators controlling, e.g., mirrors or RF switches. Within the MARIE project, electronic beamforming is a key component and can be realized in different ways. The goal of this project is to systematically compare different concepts of adaptive beamforming with each other and propose suitable concepts for specific applications at THz frequencies. The specific challenge of identifying appropriate concepts in the THz range is that, in general, devices at THz frequencies show higher losses and may exhibit molecular resonances as well as other non-idealities. Therefore, simple scaling of concepts existing at lower frequencies is only possible to a limited extent. Thus, concepts for both transmitting as well as receiving antennas are needed.

Basically, two approaches for creating THz frequencies have to be considered: electronic and heterodyne optoelectronic signal generation. Since by both principles only low transmit powers at THz frequencies are available, transmit power must not be wasted by sending it via long and lossy waveguides as well as amplitude or phase modulators. Therefore, in this project a joint optimization of signal generation and beamforming will be carried out.

Beamforming is an essential component of MARIE because of the high free space loss at THz frequencies. The project S01 will yield the first comprehensive analysis of beamforming in the THz frequency range. It jointly analyzes and optimizes generation and beamforming of THz signals. Furthermore, it combines the aspects of 3D-radar systems as well as spectroscopic information.