Dual-Band CW Radar System for Vital Signs Detection With Interference Cancellation Method

• Published in: IEEE transactions on microwave theory and techniques Vol. 73; no. 6; pp. 3581 - 3596
• Main Authors: Huan, Chang, Kontou, Panagiota, Ben Smida, Souheil, Anagnostou, Dimitris E.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2025; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Accuracy; Continuous radiation; Continuous-wave(CW) radar; Demodulators; Doppler radar; Dual band; Frequency domain analysis; Harmonic analysis; Heart beat; Heart rate; Heart rate variability; heartbeat; interference suppression; Monitoring; Noise; Radar; Radar detection; Radar equipment; Radar systems; Resonant frequencies; Respiration; respiration cancellation; Signal processing; Time domain analysis; vital signs detection; Waveforms
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2024.3494546

A novel dual-band continuous-wave (CW) radar system is proposed. The radar is designed for vital signs detection in terms of breathing rate (BR), heart rate (HR), and radar cardiograph (RCG) waveforms. The system operates at two ISM band frequencies: 2.45 and 5.8 GHz. Two five-port receivers are used as IQ demodulators. A newly developed interference cancellation method is proposed. This new method increases the reliability of heartbeat detection by canceling the interfering respiration signal in terms of its fundamental frequency component. This method is first demonstrated in the frequency domain through signal processing and second implemented in the time domain using hardware. High detection accuracy is demonstrated for several experimental scenarios. The measurement results show that the proposed system detects vital signs effectively with a relative error of less than 5% at distances (between the radar and the measured subject) of up to 2.5 m using the frequency-domain method and 1.5 m using the time-domain method.