A Self- and Mutually Injection-Locked Radar System for Monitoring Vital Signs in Real Time With Random Body Movement Cancellation

This paper presents a system for monitoring vital signs that is based on a self-and mutually injection-locked radar architecture. To detect vital signs with reduced body motion artifacts, the system uses two voltage-controlled oscillators that are self-injection locked to themselves and mutually injection locked to each other. Additionally, the system uses two different gain antennas. These features cancel out most of the body motion artifacts while preserving the vital sign signals. In the experiments, more than 85% of the body motion artifacts are removed, so the vital sign signals can be accurately monitored in real time.