Abstract
Detection of concealed weapons and explosives under people clothing is an actual task nowadays. Different active radar and passive radiometers systems that operate in mm and sub-mm (or THz) bands have been designed for screening passengers in airports. Their effectiveness is rather low at surveying people in outer clothing. The effectiveness could be improved by using dual passive-active radiometer. Such a system consists from the passive radiometer and active noise generator that emits in the same frequency band as the radiometer. The generator is working in stroboscopic mode of operation. This gives an opportunity to record two images (passive and active) simultaneously. An algorithm, that processes both images, has been proposed. It affords to reduce level of false alarms and to raise the contrast of detected objects.