Study of low terahertz radar signal backscattering for surface identification

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This study explores the scattering of signals within the mm and low Terahertz frequency range, represented by frequencies 79 GHz, 150 GHz, 300 GHz, and 670 GHz, from surfaces with different roughness, to demonstrate advantages of low THz radar for surface discrimination for automotive sensing. The responses of four test surfaces of different roughness were measured and their normalized radar cross sections were estimated as a function of grazing angle and polarization. The Fraunhofer criterion was used as a guideline for determining the type of backscattering (specular and diffuse). The proposed experimental technique provides high accuracy of backscattering coefficient measurement depending on the frequency of the signal, polarization, and grazing angle. An empirical scattering model was used to provide a reference. To compare theoretical and experimental results of the signal scattering on test surfaces, the permittivity of sandpaper has been measured using time-domain spectroscopy. It was shown that the empirical methods for diffuse radar signal scattering developed for lower radar frequencies can be extended for the low THz range with sufficient accuracy. The results obtained will provide reference information for creating remote surface identification systems for automotive use, which will be of particular advantage in surface classification, object classification, and path determination in autonomous automotive vehicle operation.

Bibliographic note

Funding Information: Funding: This work is funded by the Innovate UK (IUK) project 104268, Cognitive real time sensing system for autonomous vehicles (CORTEX), Engineering and Physical Sciences Research Council (EPSRC) [Grants No. EP/S018395/1 and No. EP/P020615/1], EPSRC/Jaguar Land Rover Plc project [Grant No. EP/N012372/1], the Royal Society [Grant No. IESnR3n183131] and the University of Birmingham [Birmingham Fellowship]. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.


Original languageEnglish
Article number2954
Number of pages17
Issue number9
Publication statusPublished - 23 Apr 2021


  • Electromagnetic scattering, Low terahertz, Radar cross-section, Remote sensing, Surface roughness, Time-domain spectrometer