Detection of trapped victims behind large obstacles using radar sensors: a review on available technologies and candidate solutions

The detection of trapped victims in natural and manmade disasters is based on tools incorporating radars for the sensing of vital signs, such as breathing and heart rate. These tools need to be low-cost, simple to use, lightweight, and quick to deploy while providing excellent estimation accuracy. Depending on the use case and target metrics, the radar systems can be developed on different technological backgrounds and the relevant literature is extensive. Herein, we review the most relevant commercially available tools and literature-proposed methods for the detection of victims behind walls and large obstacles and discuss their advantages and limitations, thus aiming to provide guidelines for the design of systems that will be efficient in a wide range of operational conditions.