Non-contact Vital Sign Detection Using Gain Detection Technique

Most of conventional vital sign radars are continuous wave (CW) radars and are based on Doppler effect. This type of radar usually faces the problem of detection null point and needs to use complex demodulation techniques to overcome this problem. To avoid the detection null point problem, this paper develops a non-contact vital sign radar using gain detection technique. This radar mainly detects vital sign signals by detecting changes in the gain of the radar signal rather than changes in the phase, so it does not suffer from the detection null point problem. Experimental results shown that the developed 2.4 GHz gain-detection-based radar can detect vital signs of subject under test very well.