Heartbeat rate measurement using microwave systems: single-antenna, two-antennas, and modeling a moving person

This paper presents a microwave system for heartbeat rate measurement. This system is based on using a vector network analyzer and horn antennas. The system generates a continuous wave signal toward a person’s chest then the reflected signal is analyzed. The phase difference between the emitted and the reflected signals contains information about the chest movement; hence, the heartbeat rate can be extracted. In this work, several scenarios for detecting the heart activity are considered. The first scenario aims to provide a comparative study for using single-antenna and two-antennas microwave systems. Several radiated powers are considered in this scenario. Simultaneously with the microwave system, a wireless electrocardiograph is used as reference in order to determine the accuracy of the system. Measurements are performed in both cases when breathing normally and when holding the breath. The second scenario aims to test the ability of detecting the heartbeat activity of a person while moving. Measurements are performed while the subject walks towards the radar. Modeling is used for this purpose. The operating frequency used is 20 GHz in both scenarios. Signals are processed using wavelet transform and results show the ability to extract the heartbeat rate even with the presence of body movement.