Microwave Inspection of Luggage for Contraband Materials Using Imaging and Inverse-Scattering Algorithms

Abstract

Microwave inspection techniques can determine frequency-dependent complex permittivity of local regions within a nonmetallic suitcase. These dielectric data can provide the additional information needed to identify contraband material, such as explosives and drugs. Although X-ray techniques provide high-resolution images of luggage contents, they cannot easily discriminate between various organic materials such as foodstuffs, paper products, and plastics. However, because common high-explosive materials and compressed-powder narcotics have dielectric properties similar to those of common plastics, dielectrometric evaluation can discriminate between contraband materials and other organics based on their moisture content or, in the case of cosmetic products, the presence of polar solvents. This paper describes the microwave luggage-inspection problem and presents an approach to discriminating and characterizing contraband materials in this environment.