Privacy Preserving Contraband Detection Using a Millimeter-Wave Dynamic Antenna Array

We present a privacy preserving technique for contraband detection using real-time 75-GHz rotational dynamic antenna array sampling only a reduced set of Fourier domain information and preventing image reconstruction on screened subject. Complex objects like handguns have sharp edges that manifest spatial frequency features in the Fourier domain. However, these features are subjected to the object’s orientation and/or being concealed under clothing. The technique combines a dynamically rotated active interferometer and simple feature extraction suggesting plausible threshold-based classifier to identify a concealed handgun; active interferometer utilizes noise transmitters to illuminate the test subject producing thermal-like radiation, enabling Fourier-domain sampling and the rotational dynamics support sampling that spans a circle in the two-dimensional Fourier domain to retrieve edge induced features. We experimentally demonstrate clear separation of concealed objects under clothing from control conditions using a 75-GHz dynamic antenna array based on simple heuristic features extracted from statistics of measured responses.