SAR processing at THz frequencies

Multistatic high-resolution sensing at THz frequencies is the goal of this research direction, with applications in many areas, such as industry, logistics, health care, and surveillance. Autofocus for THz SAR imaging is the first step in future multistatic THz SAR system development.

For many years, there has been significant development in technology for mobile communications and radar sensing. In the last decade, these two fields have been essentially merged to some degree. For example, 5G mobile communications use millimeter waves that were previously mainly used for radar and radiometer systems. For automotive radar, there have also been initiatives to use a hybrid sensor that can act as a radar and communication link to networks and other vehicles. In the development of 6G, frequencies at THz are planned to be used. This frequency range has not been explored for mobile communications or radar sensing. For 6G systems, the frequency bandwidth will be wider, and the phase noise of the oscillators in systems will be more beneficial for many applications.

In the proposed project, we plan to use, for example, 6G communication signals for high-resolution short-range sensing based on the synthetic aperture radar (SAR) principle. Modern SAR systems face different technical issues caused by the SAR platform path deviation. The path deviation influences the focus and, correspondingly, the accuracy of radar images and can be related to vibrations of the SAR platform, which is crucial for SAR imaging systems that are mounted on unmanned aerial vehicles (UAV) and operate in the THz frequency range. Thus, autofocusing algorithms are required as the first major step in the system development process.

In these projects, we aim to develop UWB SAR bistatic and multistatic autofocusing. At the beginning of the project, we start with UWB SAR monostatic autofocusing, which will be of high interest in the THz band.

Figure 1. Left: Measurement setup based on the SAR system mounted on a car; Right: Reconstructed SAR scene via the measurement system operating in the frequency range [0.22; 0.33] THz [1].

Figure 1 depicts one of the realizations of SAR systems that operate at THz frequencies. Here, the SAR system is based on FMCW radar operating in the frequency range [0.126; 0.182] THz, mounted on a car that moves at a constant speed. Furthermore, the figure contains a reconstructed SAR scene of a mannequin head from the data acquired via the system that operates at frequencies [0.22; 0.33] THz. The results were obtained in collaboration with the Institute of Digital Signal Processing, University of Duisburg-Essen; see [1] for details.

[1] Y. Ivanenko, V. T. Vu, A. Batra, T. Kaiser, and M. I. Pettersson. Interpolation Methods with Phase Control for Backprojection of Complex-Valued SAR Data, Sensors, 22 (13): 4941, 2022.

Related projects:

Multistatic high-resolution sensing at THz frequencies (Funder: ELLIIT; Status: Finished)
Fundamental and applications of bistatic SAR systems (Funder: The Crafoord Foundation; Status: Upcoming)

Kontaktperson: Yevhen Ivanenko