Detecting changes in the human heartbeat with on-body radar

Radar can be used to detect human heartbeats. This makes radar a potential alternative to today's heartbeat monitoring techniques in medicine. In this paper, two antennas were located on the chest to monitor the heart activity. Simultaneous with the radar measurements, the Electrocardiogram (ECG) and blood pressure were measured. Details of the heart activity, such as opening and closing of heart valves and the filling and ejection of heart chambers, were catched by radar monitoring. Through physical activity, blood pressure as well as the pulse of the person were increased. Matching changes were observed in backscattered radar signal waveforms, thus showing that radar can be used to detect changes in the heartbeat in a reliable way.

I. Introduction

Radar transmits electromagnetic waves and receives echos from targets within the antenna beam. When one or more of these targets change either in position or shape, it can be seen as modulations in the received signal. With low power, sensitive radar systems, small heartbeat movements can be recorded. The use of radar for physiological measurements dates back to the early seventies [1], when radar was used to monitor breathing of infants. Among the proposed applications for this technology are monitoring of human vital signs, sleep monitoring, detection of humans through the wall or through the ground and as a medical diagnostic tool. This paper will focus on the topic of using radar heartbeat measurements as a diagnostic and monitoring tool.