A Single On-Body Antenna as a Sensor for Cardiopulmonary Monitoring

In this letter, a technique to measure heartbeat and respiration rates through a single on-body antenna is addressed. The main idea is to extract the cardiopulmonary information induced on the reflection coefficient of a single antenna placed in proximity of the human thorax. As a preliminary step, phase samples of the antenna reflection coefficient have been collected by using a vector network analyzer (VNA). The heartbeat and respiration rates have been extracted from the collected data through well-known nonlinear filtering techniques that allowed us to isolate the two corresponding spectral components. The measured results show that the heartbeat and breathing data are clearly detectable, proving the effectiveness of the proposed procedure. A set of different UHF antennas has been considered, and it resulted that a better sensitivity is obtained at the lower frequencies of the UHF band.