An Overview on Millimeterwave FMCW Radar Techniques for Precise Ranging and Material Imaging

This scientific paper is an outcome of the MARIE project (for more information, see trrmarie.de) [M04]. This paper provides an overview, on recent developments as well as future challenges and prospects in measurement methods and algorithms for the determination of an object’s geometrical shape, its position, and its electromagnetic properties using FMCW radar sensors. The current research integrates radar imaging techniques with material characterization algorithms to evaluate the dielectric constant and losses, leveraging ultrawideband systems to capture dispersive features and enable µm-precise localization. Unlike single antenna synthetic aperture radar (SAR) methods, multiple-input multiple-output (MIMO) radar enhances imaging by capturing data from multiple channels and varying incident angles, enriching the information obtained. In conjunction with sensor calibration methods and radar-based material characterization, these imaging techniques provide a mobile platform for spatially resolved, precise reflection measurements in magnitude and phase that are used to derive the electromagnetic properties and, subsequently, to provide a semantically annotated material image. Due to the short wavelength and large apertures near-field wave propagation effects must be incorporated into the signal processing to achieve µm-precise ranging and imaging. Furthermore, the impact of environmental influences on the measurement accuracy must be investigated.