Automatic Permittivity Characterization of a Weak Dielectric Attached to Human Body Using Wideband Radar Image Processing

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

“…The axial cross-section images acquired via the 3D reconstruction of the HD-AIT screening system output provides quantitative information about the deformation in body surface reconstruction due to the presence of affixed foreign objects. If the deformation of the surface contour appears as a depression in the wideband radar images, the affixed object is automatically classified as lossless [43][44]. Conductive and lossy affixed materials appear as protrusions, with higher intensity than the NBC of human skin without an affixed object.…”

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

“…The estimation of the human body surface contour is necessary for the characterization of the concealed affixed objects [19,30]. We start from the observation that the radar reflectivity images of most parts of the human body are smoothly varying with respect to the circumferential angle w. However, a foreign affixed object tends to appear in the reflectivity image as a discrete depression or protrusion with rapid radial variation with respect to the circumferential angle.…”

“…The estimation of the human body surface contour is necessary for the characterization of the concealed affixed objects [19, 30]. We start from the observation that the radar reflectivity images of most parts of the human body are smoothly varying with respect to the circumferential angle φ .…”

“…The precise characterization of detected objects will result in eliminating the need for pat downs in the case of innocent objects. Such characterization necessitates clear differentiation of nominal body surface contours from the concealed attached objects [19, 30] without relying on the body's bilateral symmetry; particularly in the case of naturally-occurring body asymmetries, or with symmetrically affixed foreign objects.…”

Partial image reconstruction adapted to extracting the frequency spectrum of discrete targets in millimeter-wave AIT images

“…The ability to evaluate the composition of the targeted object without secondary screening would enhance the capability of AIT for passenger screening. [1][2][3] This method can be accomplished using data already collected as part of the imaging process by detecting how the reflectivity varies as a function of frequency. For materials that are transparent or partially transparent, the spectrum can exhibit interference effects from front and back surface reflection, which are quantified by refractive index and layer thickness via a Fresnel model.…”