Doppler radar sensing system of respiration and heart rate

In this paper, Doppler radar system is designed, which is composed of oscillator, mixer, LNA, and antennas. The idea of this paper is using reverse circular polarization for bio-detection Doppler radar to selectively receive signals reflected from highly conductive body surfaces. To improve isolation property between transmitter and receiver, we use the bistatic system using LHCP and RHCP antennas. The budget of system is analyzed and the experimental results are discussed.