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2009
Conference Paper
Titel
Standoff detection and imaging of suspicious and concealed objects with electromagnetic waves in the centimetre and millimetre range
Abstract
Dangerous and illegal objects like metallic and non-metallic weapons, explosives or drugs worn by a person and concealed beneath the clothes can be detected and imaged by means of electromagnetic waves in the centimetre and millimetre range ("microwaves"). Due to their non-ionizing nature and low power these waves are innocuous to humans. Experimental investigations have been performed on several objects at the frequencies of 94 GHz and 24 GHz. Mechanical scanning of concealed and non-concealed objects has been done with compact radar modules (broadband frequency modulated and narrowband) with different antenna types and with standoff distances in the range of several decimetres. The objects have been reconstructed three-dimensionally in short time with synthetic aperture focusing technique using Fourier transform to accelerate the calculations (3D FT-SAFT). Some examples are given of imaging of suspicious objects (metallic, ceramic, organic) concealed beneath different types of clothes. These investigations show the feasibility of a standoff personal security scanner for hidden metallic and non-metallic objects based on electromagnetic waves. The objects are detected by their contrast, shape and pattern. For specific identification of dangerous substances like explosives additional devices can be integrated (e.g. "electronic nose").