Detecting Motion in a Room Using a Dynamic Metasurface Antenna

Sensing motion and distinguishing its source as human or nonhuman, with high precision, has tremendous applications in a variety of areas from health monitoring to energy efficiency. One strategy to achieve this goal is to detect the small motion of breathing, which is a consistent indicator of human presence. Among the many smart sensing schemes proposed, microwave and RF sensors have shown great promise due to their simplicity, privacy, and effective range. In this paper, we propose the use of a dynamic metasurface antenna (DMAs) as an alternative hardware platform for sensing motion inside a residential setting using microwave signals. The proposed device is a single-port planar cavity that excites an array of electronically-tunable metamaterial elements. The DMA can generate spatially diverse patterns at a single frequency, avoiding complexities related to wideband operation or high hardware costs of antenna arrays. We demonstrate that it is capable of detecting minute movements, such as breathing emulated by a mannequin, to distinguish human presence. This motion can be detected whether the target is in the the sensor's direct line of sight or out of the direct line of sight. Furthermore, we show that the DMA sensing platform requires a single noise-floor calibration and can operate in different room geometries or configurations (e.g. when furniture is displaced). The proposed DMA-sensor with its single frequency operation and simple hardware is an appealing alternative hardware for intruder detection, human presence detection/activity recognition in smart homes, or seamless health monitoring.