An electrical engineering professor at the University of Michigan believes that a type of radar, part developed by the Department of Defense, has the potential to be used as a means of detecting concealed weapons. Originally intended for military use, it is possible that the millimeter-wave radar system could be used to detect weapons across distances as large as a football field.
Professor Kamal Sarabandi was watching the aftermath of the Newtown shooting in Connecticut when he was hit by the notion that his work for the military may have a use a little closer to home.
The technology that he developed is currently being used in a number of applications, including collision avoidance systems in cars and in military targeting systems. The radar itself isn’t particularly unique, but Sarabandi’s pairing of the tech with Doppler radar signal processing allows it to pick out an individual in a crowd using a technique called polarimetry.
Doppler radar has a range of applications from speed traps to predicting the weather, using the Doppler effect to measure the speed of a given object. Sarabandi used motion capture techniques to identify the reflected signals from the limbs and torso of a human walking, creating what he calls “the DNA of walking.”
A computer is programmed to recognize the pattern, searching for a particular glare on the subjects chest, such that a hidden metal object might create. The technology focuses on the pedestrian’s chest as it’s both a common place that people hide weapons and acts as a fairly smooth backdrop, making it easier to pick out anomalies.
The polarimetric radar used by the team works by sending out a signal at a particular polarization, and carefully analyzing the polarization of the signal that bounces back. An irregular metal object can change the polarization of the signal, allowing for the detection of concealed items.
Though the technology has not yet undergone any human testing, Sarabandi’s team has carried out a simulation using a mannequin painted with a coat that reflects radar-like human skin. The mannequin was placed on a turntable in an anechoic chamber, a room designed to absorb all echoes and reflections.
The techniques could be used to scan large groups of people, with each subject taking less than a second to process. This would then allow security personnel to closely observe the individual in question or even take suspects aside for more comprehensive scans.

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