SAR imaging-based techniques for Low Permittivity Lossless Dielectric Bodies Characterization

Abstract

The following contribution aims to test two synthetic aperture radar (SAR)-image-based techniques to obtain geometry and constitutive parameter information about low-permittivity lossless dielectric materials. While characterization of high-permittivity dielectrics is relatively affordable in SAR images, the low amount of power reflected back by lowpermittivity bodies makes their characterization a challenging task. The first proposed technique combines two illumination angles (normal and 45 ) to overcome the permittivity-geometry uncertainty appearing on each independent case. The second method makes use of the relationship between reflection coefficient amplitudes between two media, which can be directly extracted from the SAR image to provide an estimation of the dielectric object permittivity. Uncertainty of both techniques can be reduced by properly combining them. We validate these methods using a simulation-based application example in the form of a millimeter-wave portal-based system for concealed-object detection.

Fast, Fully-Automatic Characterization of Metallic and Water-Based Threat Objects for Millimeter-Wave Personnel Screening Systems

“…Near field mm-wave imaging systems are the primary means of detecting concealed metallic weapons such as handguns [19]. Various studies have shown that synthetic aperture radar (SAR) images can be used for accurate identification and characterization of weak dielectric objects on the body surface [20][21][22]. Recent studies have discussed the feasibility of weak dielectric characterization using a focused continuous wave radar scanning system by developing a ray-based virtual source model [23][24][25][26].…”

Determining the nominal body contour image using wideband millimeter-wave radar for characterizing person-worn threats

“…Yurduseven et al proposed a fast simulation of full-size frequency-diverse aperture for imaging of humanscale targets [16]. Alvarez et al demonstrated the feasibility of synthetic aperture radar screening to estimate the geometry and constitutive parameter information for low-permittivity lossless dielectric objects attached to flat and curved metallic plates [19][20][21]. Focused-beam continuous-wave radar was used for object characterization in security applications [23][24][25].…”

Automatic characterization of low-loss low-permittivity body-born threats using wideband millimeter-wave radar

“…Our study focuses on determining the same properties of the potential threats automatically and by using wideband radar images with high range resolution. In [29,36], it has been shown that synthetic aperture radar (SAR) imaging can be used for deriving such characteristics for low-permittivity and lossless foreign objects. We apply the same method to our wideband radar images.…”