A 75GHz Dynamic Antenna Array for Real-Time Imageless Object Detection via Fourier Domain Filtering
We present a millimeter-wave dynamic antenna array operating at 75 GHz that can identify strong spatial Fourier domain artifacts in real-time for object detection without image reconstruction. Objects with sharp edges manifest broad-spectrum spatial frequency signals in the spatial Fourier domain that are located at angles orthogonal to the edge direction. The presented technique is based on active interferometry where noise transmitting sources are implemented to illuminate the scene of interest by mimicking thermal radiation. With rotational array dynamics, a one-dimensional (1D) array comprising of two transmitters and two receivers synthesizes a ring-shaped sampling function collecting sparse spatial Fourier information. In this way, broad-spectrum signals are captured, which can then be used for shape characterization. While the approach enables object classification, it does not sample enough information for full image reconstruction, which is beneficial for privacy preserving in contraband detection. We experimentally demonstrate the detection of simple objects with reduced information acquisition compared to full imaging systems.