Passive Millimeter-Wave Imaging for Security

How It Works Unlike X-Ray systems with their ionizing radiation, and active Microwave systems which bathe the subject in RF, passive millimeter-wave (PMMW) imaging systems read the natural thermal energy in environment, much like an infrared camera. Unfortunately, infrared wavelengths are too short to pass through clothing, so we choose a longer wavelength of 3 millimeters (specifically 80 to 100 GHz) to detect and image thermal energy in the environment (see Fig. 1). Heat coming off 100 GHz LNAs and detectors and attention to engineering details make frame-rate whole body passive millimeterwave imaging a reality today.