| Radar technology, long limited to military applications, is now available to the civilian sectors such as automotive collision warning in traffic controls and safe navigations, and in the biomedical sector for the development of systems of non-invasive monitoring of patient's vital signs such as breathing and/or heartbeats. Positioned over the ceiling of a hospital care room, such RF systems can monitor the cardiological activities or respiratory status of several patients simultaneously. With these systems it is also possible to give a fast emergency alarm in the case of a sleep apnea syndrome or sudden death in neonates. Another application is the monitoring of vital functions of the foetus inside the womb of a mother during abnormal pregnancy. In a somewhat different context, these RF biomedical systems are currently designed for surveillance of high security areas or for searching and rescuing of survivors after earthquakes or other disasters. For this last application, the RF system must be able to do two functions: the vital signal detection and the local positioning.;Three systems operating at different frequencies were built up: 5.8 GHz, 24 GHz, and 35 GHz. The choice of frequency is justified by the trend of miniaturization and to fulfill the ISM band (Industrial, Scientific and Medical) specifications. Besides the frequency of operation, these systems also differ in their architectures and technologies. Their experimental performances are compared and discussed. In addition, different signal processing methods are used to separate the heartbeat signal from its respiration counterpart, and the experimental results are compared while some important conclusions are reached.;The objective of this research project is to design a Doppler radar system to detect the heartbeat and respiration status of a patient without direct skin (invasive) contact. An analysis of the proposed system taking into account the electromagnetic wave propagation in human tissue is proposed. In addition, several prototypes are fabricated and tested. The design, simulation results and measurements are presented in this thesis. |
