Improved Threat Detection in Walk-Through Security Scanning Using an Optimized Polarimetric Target Decomposition Method

Abstract

Reliable and convenient walk-through security scanning, which doesn't separate people or impede their movement, is an extremely challenging task. In this paper, a novel approach for a security check with an overhead observation and a polarimetric target decomposition is presented. The viewing angle of the scanner equals a side-looking airborne radar. However, it will be shown that the established polarimetric target decomposition methods of remote-sensing are not well suited for close-range radar imaging and need to be adapted due to the differences in the geometry of the imaging scenario. The usage of a multiple input and multiple output (MIMO) array and the shorter distance between array and target need a changed decomposition technique in order to distinguish between persons with or without worn threat objects. The differences between radar remote-sensing and close-range imaging scenarios are investigated. An optimized version of the Sato four-component polarimetric scattering decomposition is derived. The proposed close-range adjustment is applied to the model and investigated experimentally with a 4-to-12 GHz fully polarimetric MIMO imaging system. Polarimetric decomposition is carried out on defined test structures with known scattering mechanisms, as well as on mannequins and persons with different threat objects like guns or explosives. In test campaigns, promising results were achieved for a correct target decomposition in radar-based walk-through security scanning.

Data Compression for Close-Range Radar Imaging

“…Some work has been conducted in the context of surveillance [7] and remote sensing with synthetic aperture radar (SAR) [8]- [10] or inverse SAR (ISAR) [11]. However, as demonstrated, for example, in [12], close-range radar data which we target in this paper, are different from typical remote sensing data. For close-range applications, only one study has been conducted [13].…”

3D Printed Hemispherically Radiating Antenna for Broadband Millimeter Wave Applications

“…In smart home applications, i.e., assisted living [12], [13], lighting and ventilation control and vital signs [3], [14], [15], the dimensions of the rooms are minuscule and thus a small field of view (FoV) may lead to blind spots. In security [16], [17], and medical [18], [19] applications, people are usually very close to the sensors, which means that huge FoVs are required to be able to detect and sense the entire body. Whereas omnidirectional antennas are desired for communication applications (e.g., Wi-Fi), hemispherical coverage is preferable for the above-mentioned applications.…”