Vital Signal Detection for Continuous-Wave Radar Sensor using Compensation Technique

A beam-controllable radar sensor and its signal processing are proposed for improving sensitivity in vital signal detection caused by static clutters. The main beam direction of the continuous-wave radar sensor is adjusted by controlling the single-pole single-thru (SPST) RF switches configured in the series patch antenna array. The periodic change of the radar beam direction generated by continuously controlling the switches causes modulated signals at the baseband. The vital signals can be extracted from the separated baseband signals by the envelope detection method. The signal-to-noise ratio (SNR) of the vital signals is increased from the processing gain of the modulated signals by using the cross-correlation technique including the detrending method. Experimental results showed that the SNRs of respiration and heartbeat detection were increased by 5.2 dB and 6.6 dB, respectively, by beam switching and signal processing of the proposed radar sensor.