Microwave and Millimeter-Wave Radars for Vital Sign Monitoring

Abstract

Doppler radar has been widely used for remote sensing applications for many years, including velocity measurement, navigation and position sensing, weather sensing, automobile speed sensing, and vital sign detection. In principle, a Doppler radar transmits a continuous wave (CW) toward a moving target and measures the relative velocity by detecting the frequency shift in the received signal as illustrated in this chapter. The chapter starts with the working principle of CW Doppler radar, including radar architecture, the choice of radar carrier frequency, and the design consideration about DC offset, phase noise, and in-phase and quadrature (I/Q) imbalance. It also reviews the digital intermediate-frequency (IF) Doppler radar, baseband signal processing methods dealing with signal distortion and nonlinear phase modulation effect, and random body movement cancellation. Finally, the chapter presents a 60 GHz radar for the detection of respiration and heartbeat of human and laboratory animal.