Four-Channel PQSIL Radar for Remote Vital Sign Monitoring With Clutter Effect

This study proposes a 2.4 GHz four-channel phase- and quadrature self-injection-locked radar for vital sign monitoring in cluttered environments. Effective clutter immunity was achieved using modified principal component analysis (MPCA) and channel compression demodulation (CCD). MPCA mitigates clutter by reorganizing signals and canceling out unwanted components, while CCD compresses trajectories, making it less sensitive to clutter. Displacement monitoring experiments of human chest motion at a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3-\mathrm{m}$</tex> range demonstrated that both methods successfully extracted respiration and heart rates, even in cluttered environments.