Microwave life-detection systems for searching human subjects under earthquake rubble or behind barrier

Abstract

A new sensitive microwave life-detection system which can be used to locate human subjects buried under earthquake rubble or hidden behind various barriers has been constructed. This system operating at 1150 MHz or 450 MHz can detect the breathing and heartbeat signals of human subjects through an earthquake rubble or a construction barrier of about 10-ft thickness. The basic physical principle for the operation of a microwave life-detection system is rather simple. When a microwave beam of appropriate frequency (L or S band) is aimed at a pile of earthquake rubble covering a human subject or illuminated through a barrier obstructing a human subject, the microwave beam can penetrate the rubble or the barrier to reach the human subject. When the human subject is illuminated by a microwave beam, the reflected wave from the human subject will be modulated by the subject's body movements, which include the breathing and the heartbeat. If the clutter consisting of the reflected wave from stationary background can be completely eliminated and the reflected wave from the human subject's body is properly modulated, the breathing and heartbeat signals of the subject can be extracted. Thus, a human subject buried under earthquake rubble or hidden behind barriers can be located. This system has been tested extensively in a simulated earthquake rubble in the laboratory and also in a field test using realistic earthquake rubble conducted by a Federal Emergency Management Agency (FEMA) Task Force.

A non-contact vital sign monitoring system for ambulances using dual-frequency microwave radars

“…We have previously also reported the non-contact method using a ceiling attached microwave radar to monitor the respiratory rates of subjects in bed through thick bedding [10] and attached it to the back of a chair to monitor the change of autonomic activation [9]. The method can be performed without thick bedding removal because microwave radar, which has been studied for use in locating human subjects buried under earthquake rubble [1][2][3]6], has no trouble penetrating thick bedding.…”

An approach to a non-contact vital sign monitoring using dual-frequency microwave radars for elderly care

“…The aim of using this radar method was to measure motion on an extremely small scale which occurs on the body surface as a result of cardiac and respiratory activity. This method was originally developed for searching for survivors under earthquake rubble [11,12]. We have also previously developed a non-contact vital sign monitoring system using dual-frequency microwave radars (10 GHz and 24 GHz) for measuring the vital signs of casualty patients inside a moving ambulance [13].…”

Micro-Doppler analysis and application of radar targets

“…If the reflected wave from the stationary background can be cancelled and the reflected wave from the subject's body is properly demodulated, the breathing and heartbeat signals of the subject can be extracted. Thus, a human subject buried under the rubble or the debris can be located [22]. By using a low-power RF waveform source and then examining responses of the return waveform after it has interacted with the engine.…”