Fully-polarimetric passive MMW imaging systems for security applications

Increasing terroristic attacks raise the danger to the public and create a new and more complex dimension of threat. This evolution must and can only be combat by the application of new counter-measures like advanced imaging technologies for wide-area surveillance and the detection of concealed dangerous objects. Passive microwave remote sensing allows a daytime independent non-destructive observation and examination of the objects of interest under nearly all weather conditions. The acquisition of polarimetric object characteristics can increase the detection capability by gathering complementary object information. Over years the DLR Microwaves and Radar Institute developed several problem-orientated radiometer imaging systems covering nearly the whole frequency spectrum between 1 GHz and 100 GHz for a multitude of applications. Actually a fully-polarimetric radiometer receiver at W band is developed in order to explore the polarimetric information content of interesting objects simultaneously. Some important theoretical characteristics of polarimetric radiometry at millimeter-waves are introduced and discussed. The actual design and construction of the receiver system is outlined and first experimental imaging results are presented.