Development of passive millimeter wave imaging for concealed weapon detection indoors

The passive millimeter wave (PMMW) imaging is often successful for outdoors as radiation of natural sky (cold source) provides the required contrast for imaging. When this method is used indoors, to detect weapons hidden inside the human body they fail detection due to the contrast between the target and subject being not obvious from lack of sky radiation. An active illumination although provides the desired contrast for the image recognition, but cause the image blind and flicker resulting in poor quality of imaging and target identification. This article describes a PMMW imaging security systems suitable for indoor usage. This system includes a large-diameter parabolic antenna for convergence of target radiation, a front end array consisting of 9 94 GHz imaging radiometer, eight Ka-band source with discrete frequency and discrete radiation direction to radiating harmonic illumination, and provide affordable energy like noise radiation, avoiding image's glint under coherent radiation. The results obtained from experiments on indoor detection of concealed weapon in human body validate the theory of proposed imaging systems, its feasibility, and practical utility. (c) 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1701-1706, 2014