Microwave weapon will rain pain from the sky

[Eugen Leitl]

(and a realtime multitarget beamforming phased array to boot)

http://www.newscientist.com/article/mg20327185.600-microwave-weapon-will-rain-pain-from-the-sky.html

 Microwave weapon will rain pain from the sky

    * Updated 17:09 23 July 2009 by David Hambling

    * Magazine issue 2718. Subscribe and get 4 free issues.

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THE Pentagon's enthusiasm for non-lethal crowd-control weapons appears to
have stepped up a gear with its decision to develop a microwave
pain-infliction system that can be fired from an aircraft.

The device is an extension of its controversial Active Denial System, which
uses microwaves to heat the surface of the skin, creating a painful sensation
without burning that strongly motivates the target to flee. The ADS was
unveiled in 2001, but it has not been deployed owing to legal issues and
safety fears.

Nevertheless, the Pentagon's Joint Non-Lethal Weapons Directorate (JNLWD) in
Quantico, Virginia, has now called for it to be upgraded. The US air force,
whose radar technology the ADS is based on, is increasing its annual funding
of the system from $2 million to $10 million.

The transmitting antenna on the current system is 2 metres across, produces a
single beam of similar width and is steered mechanically, making it
cumbersome. At the heart of the new weapon will be a compact airborne
antenna, which will be steered electronically and be capable of generating
multiple beams, each of which can be aimed while on the move.  The new
antenna will be steered electronically and is capable of generating multiple
heat beams

The ADS has been dogged by controversy. J|rgen Altmann, a physicist at
Dortmund University in Germany, showed that the microwave beams can cause
serious burns at levels not far above those required to repel people. This
was verified when a US airman was hospitalised with second-degree burns
during testing in April 2007.

The airborne version will not make it any less contentious. "Independent of
the mode of production, with this size of antenna the beam will show
variations of intensity with distance - not just a simple decrease - up to
about 500 metres," says Altmann. Shooting it on the move with any accuracy
will be difficult, he adds.

Dave Law, head of the technology division of the JNLWD, says the new antenna
will operate at the lowest possible effective power level and will have a
sophisticated automated target-tracking system.

In a recent cost-benefit analysis, the US Government Accountability Office
rated the ADS worst out of eight non-lethal weapons currently in development.