The research and design of an active millimeter-wave concealed object imaging system is described. Several illumination and detection methods were analyzed via computer simulation to assess the effects of system parameters on the signal-to-noise ratio of the detected signal. The results of many of these simulations were experimentally verified using either a 10 MHz or a 100 GHz measurement system. Based on this assessment, two design using pulsed illuminate with gated detection were selected for development. Pulsed illumination is provided using a pulsed broadband noise source. For detecting the reflected noise pulse, two methods were examined, one using micro bolometers and the other using electrooptics. Based on imaging system considerations, such as cost of manufacture, ruggedness, etc., and technical parameters, micro bolometer arrays were selected for further development. The electronics interface, including image display capability, was developed. We examined the absorption of some common clothing materials at 100 Ghz and compared this to results previously reported.