Passive Millimeter-Wave Imaging Technology for Concealed Contraband Detection

In this chapter, we firstly introduce the fundamental radiation detection theory of the passive millimeter-wave imaging technique for human-body security inspections. A radiation temperature transfer model for the passive millimeter-wave near-field imaging is then proposed. The method to analyze the temperature contrast between the human body and the concealed objects under indoor and outdoor environments is presented accordingly. Furthermore, several key technologies involved in the passive millimeter-wave imaging systems are discussed in detail, including the millimeter-wave radiometer, the millimeter-wave feed antenna, the focusing antenna, and the quasi-optical theory. Finally, a prototype of a Ka-band passive millimeter-wave imaging system based on the focal plane array is manufactured. The system design process and the measurement results for some typical scenarios are elucidated.