Computational through-wall imaging using a dynamic metasurface antenna

We present a study of computational through-wall imaging using a dynamically reconfigurable metasurface antenna (DMA). The DMA consists of a single-feed, electrically-large microstrip line, loaded with individually addressable metamaterial radiators. Each metamaterial resonator is integrated with a diode, enabling it to be switched on (radiating) or off (non-radiating) by an externally applied voltage. By switching subsets of the array of elements on or off, spatially diverse radiation patterns are formed that are scattered by the wall and structures beyond the wall. Images can be reconstructed from these measurements, using a combination of range migration algorithms and wall compensation algorithms, with minimal frequency bandwidth requirements; even single frequency measurements are possible in conjunction with the DMA. We investigate imaging through a variety of wall materials at K-band frequencies (18-26.5 GHz), including homogeneous media with known properties and inhomogeneous materials such as plywood. We further investigate single-frequency performance against full-bandwidth measurements. The DMA used here is electrically large in one dimension, over which many spatially diverse measurements can be taken. By scanning the DMA in the perpendicular direction, full two-dimensional scans can be acquired with minimal cost and time, making the one-dimensional DMA attractive as the basis for future through-wall scanning systems.