A Dynamic Antenna Array for Imageless Contraband Detection

Abstract

We present and experimentally demonstrate a novel approach to contraband detection using sparse Fourier domain sampling with a dynamic antenna array. A 38-GHz two-element antenna array is dynamically rotated to generate a ring-shaped filter in the Fourier transform domain of a scene, or the spatial frequency domain, where unique responses from contraband are identified, without image reconstruction. Objects with sharp edges generate sharp yet broadband spatial frequency responses that can be identified with only a subset of the spatial frequency information. In contrast to other millimeter-wave contraband detection approaches, the presented system does not depend on a fully reconstructed image nor has the ability to form one. In the presented technique, only a subset of all available spatial frequency samples are measured by the two-element dynamic antenna array with the objective to identify the strong broadband spatial frequency responses associated with sharp edges. Conducted measurements include a fabricated knife prop as contraband concealed under clothing, along with a control scenario. Measurement results demonstrate the ability to recognize a metal object, and furthermore indicate the ability to identify the shape of the target based on the responses from the knife edge as well as the angled tip that are visible in both simulation and measurement.