Phased Array with Non-Ideal Double Phase Shifters for Multi-Target Vital Sign Monitoring

A phased array equipped with double phase shifters (DPS) can reduce interference and enable multi-target vital sign monitoring (VSM) based on a single receive antenna. The DPS-phased array can control both the magnitude and the phase of the signal transmitted by each antenna, allowing for flexibly creating a desired beampattern. We consider the DPS-phased array weight design problem, taking into account practical constraints on the phase shifters, such as deviations from the nominal phases and insertion loss. The weights of practical phase shifters are selected so that the resulting DPS-phased array performs as close as possible to an ideal beamformer and transmits maximum power in the desired direction. The proposed design's effectiveness is demonstrated in experiments where the transmit power is focused on a specific human target to monitor corresponding vital signs. Simultaneously, an adjacent but unwanted human target is effectively nullified.