Heartbeat Detection based on Signal Reflected from Antenna in Mobile Device
In this paper, human heartbeat detection using signal reflected from the antenna which is varied reflection coefficient by near field variation of the antenna. For detection reflected signal from antenna, 20 dB directional coupler is used because of not affecting transmitting signal. Variance of reflection coefficient of dipole antenna is about 0.07 dB which is too small the distinction between heartbeat and noise. Sensitivity increasing method is applied and heartbeat is clearly detected. Due to phase and magnitude errors come from discrete value components, antenna is located some points in experiments ro find optimum sensitivity position. And providing verification of using communication signal, heartbeat detection when frequency modulated signal which have 4 MHz bandwidth is applied.