Study of Low Terahertz Radar Signal Backscattering for Surface Identification

Shahrzad Minooee Sabery,Peter Gardner,Aleksandr Bystrov,Miguel Navarro-Cía,Marina Gashinova

doi:10.3390/s21092954

Abstract

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.

Highlights

In recent years, radars operating in the low THz range, from 0.1 THz to 1 THz, have been developed for a wide range of applications such as standoff personnel screening [1], material characterization [2] and, importantly, have been proposed as a candidate radar to provide high-resolution imagery for future autonomy [3,4,5]
The focus of this research is on studying the low THz signal backscattering from surfaces with different roughness
The aim of this work was to study the characteristics of low THz signal reflection from surfaces with different roughness in terms of applicability in automotive radars

Summary

Introduction

Radars operating in the low THz range, from 0.1 THz to 1 THz, have been developed for a wide range of applications such as standoff personnel screening [1], material characterization [2] and, importantly, have been proposed as a candidate radar to provide high-resolution imagery for future autonomy [3,4,5]. The use of such radars allows an autonomous vehicle to effectively classify road objects and perform route planning [6,7]. The high cost was an obstacle to the widespread implementation of low THz radar systems, but with the development of appropriate technologies [13], it has been steadily decreasing

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