Respiratory rate measurements via Doppler radar for health monitoring applications

This paper presents experimental results for measuring respiratory rate using non-contact and low power system for health-monitoring applications. The system is based on a Doppler effect. A mechanical setup with controllable movement frequency and displacement was built to mimic the human chest movements while breathing. A Doppler radar system was used to measure the frequency of the proposed system. Three different antennas were used to study the effect of antenna radiation pattern, gain, and cross-polarization on the accuracy of the measurements. An error analysis was conducted for different frequencies and displacements. Results demonstrated that the antenna of a moderate directivity and gain values, and of the least cross-polarization components has higher accuracy compared to other proposed antennas. It can be concluded that with a good selection of antenna it is possible to measure respiratory rate with a small error using the proposed radar system.