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British scientists have developed a portable microwave scanner to help police identify individuals carrying concealed guns and knives.

It is small enough to be used covertly, at some distance from the subject.

The device is based around microwave radar technology and is designed to pick up the "reflections" of weapons concealed beneath clothing.

It could help increase the effectiveness of stop-and-search.

The existing prototype is suitable for the detection of guns, but researchers say subsequent versions of the technology will be able to identify concealed knives as well.

The new device employs low-power microwaves to identify weapons, using similar wavelengths as the body scanners currently in use at a number of airports.
Unlike airport scanners, the portable machine does not produce an image of the subject, it only analyses signals.It is designed to work out on the streets and is not (restricted) to a closed, controlled environment

Return signals - microwaves reflected back towards the device - are picked up, sensed and analysed. The scanner does a lot of computing and processing of the signals it acquires. It puts them all together, analyses them over a short period and makes a decision

Neural network technology is employed to identify signals from concealed weapons and to ignore those from everyday items. Similar technology is used in the automatic recognition of car number plates.

If trials are successful, this device could become available to police forces within two years.

Link - BBC News