Development of Multifrequency MW Detection Device to Scan Liquids in Security Checkpoints

Development of both technical devices and effective methods for the detection of various dangerous substances is one of the critical task in providing airport and critical infrastructure security. In this work, we propose to use MW technique, based on probing dielectric permittivity parameters of liquids, as a prospective technique for detection of most frequently used energetic, flammable, chemically-active and other classes of dangerous liquids. Approaches for the MW detection with increased discrimination ability are presented. A device, combining several sensors for various frequencies with various probing distances, has been designed and tested. Several issues have been successfully resolved in the process of the development of this device: 1) placing various sensors in the most effective and compact manner to scan of bottles of various size; 2) a minimal cross-talk between various sensors; 3) effect of distance variations between the sensors and a scanned bottle. For minimization of the device cost and easy commercial implementation, low MW electronic components and units have been used to construct this device. A set of various sensors for frequencies between 1-4 GHz have been developed. A signal acquisition, processing and user-interface software have been also developed. The first experiments with the PET bottles with various liquids have been done.