Electromagnetic environment comprehension for radar detection of vital signs at China National Training Center for earthquake search & rescue

Previous studies have demonstrated that the radar technique is one of the most effective ways to detect human vital signs in certain circumstances. However, the problem of the complex electromagnetic environment at an earthquake disaster site has not been fully explored in the literature to date. To characterize and comprehend the electromagnetic environment in radio frequencies in a typical field site for the task of search and rescue by using radar technology to search for human vital signs originated from buried living victims we conducted a field test to collect data by using the 400-MHz ground penetrating radar on a one-to-one scale collapsed building model at China National Training Center for Earthquake Search & Rescue (CNTCESR) operated by China Earthquake Administration (CEA) in Beijing. The physical model is a collapsed 3-storey reinforced concrete building. Both constant-offset and multi-offset reflection profiles are collected on the relatively intact roof of the building with a size of 17 × 12 m. The constant offset (monostatic) reflection profiles are collected at 10-cm spacing in-line and 20-cm spacing off-line to cover a 15 × 10 m area. Multi-offset profiles are collected at a few given locations. The time window for all radar profiles is 100 nanoseconds. We used the digital point-cloud technique to construct the 3D digital model of the collapsed building. This 3D model is the basis for conducting radar wave propagation forward modeling and inversion imaging. The awareness and comprehension of the ambient electromagnetic condition will be incorporated in the algorithm for radar detection of human vital signs for earthquake victim search and rescue in real world field practice.