| The passive millimeter-wave (PMMW) imaging technology has adopted in a widerange of military and civil practical applications, such as remote sensing, blind landing,navigation and security scanning. Because of good transparency of the clothing atmillimeter wave band, a millimeter wave radiometer can be used to image and distinguishconcealed contraband beneath clothing, for example guns, knives, detonator, etc. In othercountries, such as the Britain and the USA, the research on the PMMW imaging system,used for distinguishing concealed contraband beneath clothing, has already been developedmore-maturely, so called to the second generation. However, in China, this research is stillfresh and is restricted by millimeter-wave technics, components and test instruments. Theresearch on the millimeter-wave radiometric imaging used for detecting contrabandconcealed beneath clothing is systematically analyzed in this dissertation, which includesthe fundamental theory of millimeter-wave radiometric measurement, the design andimplementation of a millimeter-wave radiometric imaging system, the imagereconstruction and super-resolution restoration and the imaging experiments carried outindoors etc. The main research can be summarized as follows:(1) The comprehensive analysis is undertaken on the development of PMMWimaging technology both in home and foreign counterparts in this paper. Then, thetechnological challenges and the corresponding resolutions in the development of PMMWimaging technology used in the detection of concealed contraband in others countries, arealso presented here. Further more, we establish the research direction and content of thispaper.(2) The model of the antenna temperature contrast between concealed contraband andhuman body indoors and outdoors is analyzed. And the relationship between the antennatemperature contrast and the transmittivity of clothing, in different wavebands (Ka-bandand W-band) and different environment temperatures (indoors and outdoors), is discussedin detail. Transmittivities of clothing with different materials and different thickness aretested in a RF anechoic chamber at Ka-band and W-band respectively.(3) The W-band two-dimensional (2D) planar scanning radiometer imaging system isintroduced, which includes a dual-beam lateral defocusing Cassegrain antenna, a receiverof the W-band two-channels total power radiometer, a 2D planar scanning system, a data acquisition and control module, and image processing:software. Based on the calculationand analysis of system parameters, such as receiver sensitivity, receiver system gain,spatial resolution, scanning rate and sampling rate, the system design is implemented andsome primary experiment are carried out.(4) The factors,which result in the image deterioration in the imaging system, arediscussed and the PMMW imaging model is set up in this paper. Restoration of the imagesacquired by the PMMW radiometer is studied by means of restoration techniques such asthe Winner-filtering. Meanwhile, in order to decrease the image moving fuzziness causedby the scanning, the point spread function (PSF) parameters of system movement areestimated by means of prior fuzzy identification. Owing to the inherently poor spatialresolution of the PMMW image, a Projection-Onto- Convex- Sets (POCS) algorithm isused to restore image to enhance the super-resolution performance. Based on simulationand test, parameters of the algorithm are achieved and satisfying PMMW images arerestored.(5) Indoors, the temperature contrast between concealed contraband and backgroundbecomes less, which makes the blurred image from this imaging system. A wide-bandnoise source is employed to illuminate the scene in order to achieve greater contrast, andexperiment results clearly show the method very effective in the paper.
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