Raytheon brings heat-ray Silent Guardian to market

Published 15 October 2007

The interest in non-lethal weapons grow, and Raytheon brings its Silent Guardian to market — a system which emits a beam of millimeter-wave energy to induce an “intolerable heating sensation”

That Taser guns are havng their problems does not mean that interst in non-lethal weapons is subsiding. The opposite is the case. In evidence: Research into using the heating effect of millimeter waves as a weapon has yielded a device which has been brought to market by the Tucson, Arizona-based Missile Systems division of Raytheon. The device is called Silent Guardian and it uses the heating effect of a beam of millimeter-wave energy to induce what the company calls an “intolerable heating sensation.” Some obervers have questioned whether the weapon is useful for its declared purpose — for controlling crowds and individuals in open ground — and have further argued that it could be used more easily for torture. For example, you tie a person down so he cannot escape, then beam him with system.

EE Times’s Peter Clarke writes that

research was conducted into the use of 95 GHz frequency waves as an antipersonnel “heat ray” against crowds and insurgents during the 1990s.

At the time the weapon, called Active-Denial Technology, had already been in development for ten years at the Kirtland, New Mexico-based Air Force Research Laboratory (AFRL) in tandem with the Joint Non-lethal Weapons Directorate of the Marine Corps. About $40 million had been spent developing the weapon, according to AFRL. The technology was described as producing a heating effect in the top 1/64 of an inch of the skin. It is reported that a two-second burst of energy from the system can heat the skin to a temperature of 130° F. An AFRL fact sheet produced at that time said, “active-denial technology will not cause rapid burning, because of the shallow penetration of the beam and the low levels of energy used.”

Now Raytheon has produced a datasheet on Silent Guardian saying that it has designed, developed, and manufactured the technology. The beam size, whether it is a convergent focused beam or a divergent beam and the range, were all described as classified information in 2001. Raytheon has said in its datasheet that the beam is focused and illustrated it as being convergent. It describes the range as being in excess of 250 meters. The datasheet and a video of the Silent Guardian and its target-tracking could be found here when this story was first posted.

Note that countermeasures against directed energy weapons at millimeter-wave frequencies could be quite straightforward. Experts point to covering up the body with thick clothes or carrying a metallic sheet, or even a trash can lid, as a shield or reflector. It remains unclear how the active-denial technology would work in rainy, foggy, or sea-spray conditions where the beam’s energy could be absorbed by water in the atmosphere.