Natanael L β€’ March 16, 2012 7:19 AM

2 in 11 000 exposures has required medical attention? That’s the same as 1 in 5500. Imagine a large demonstration of several thousand people. How do you know it won’t go bad?

Also, how do you know what it does to electronics? Then I mean phones, etc. Pacemakers should not be reached by the signal, unless there’s a second device above the skin too.

Also, skin cancer risk?

I’d prefer standard IR.

Natanael L β€’ March 16, 2012 7:21 AM

Also: What about those forrest fire aluminum sheet covers? You could easily walk around in one of those.

Tin-foil hats FTW! πŸ˜›

(Note: a mod could combine my posts into one, if you’d like.)

Nicholas Weaver β€’ March 16, 2012 7:26 AM

Nathael: 1 in 5500 exposures requiring medical attention (which can include, eg, paniced falls) is orders of magnitude less than what you see with things like beanbag rounds, tear gas, etc.

And firefighter sheets do work, as long as they block you completely. A little bit of a gap and, OW!

The problem is warmup time, rain, and perception.

An excellent report from Spencer Ackerman at Wired.

NZ β€’ March 16, 2012 7:45 AM

“In contrast, microwave frequency is around one gigahertz, which moves faster and penetrates deeper”
Moves faster???

karrde β€’ March 16, 2012 8:18 AM

I think I’ve seen the concept discussed before.

However, a demonstration of a field-ready device is a step up from a proof-of-concept.

I thought I’d seen a claim that this system has a long warm-up time. (Hours, not minutes.) That may be what keeps the Pentagon from ordering the devices.

@NZ, that is pretty bad. I suppose that the reporter misunderstood a statement that microwaves “move further and penetrate deeper”…but it could be that they simply wanted to say something “moved faster”.

Clive Robinson β€’ March 16, 2012 9:03 AM

@ Bruce,

No details on what “non-lethal” means in this context

It means that the target is far enough away and the operator has not turned the wick up to far for faster results (remeber the inverse square law that energy drops off with distance).

I’ve given the details before but you can strip down a conventional microwave oven and battery based UPS and build them into a technician style brief case (I’ve done it).

Experimental results with bits of dead pig showed that with a 650W microwave and 1KW UPS with smaller seald lead acid batteries could provide enough energy to cook the spinal cord to protein depolorisation in 10-30 seconds close up (ie 40C or above). And as a secondary advantage could cook the whole pork chop for dinner in about four times that…

The important point is that in this case it was a configured as a “near field” device, that is within two wavelengths of the antenna aperture. The freespace loss at two wavelengths is normaly given as 17dB (~1/50th) which when you work it out is quite significant over a relativly short distance of 24cm at 2.4GHz (the reason microwave oven cavities can be larger is the energy is contained in the cavity and either ends up being absorbed by the food or going back into the RF source and damaging it with a very high Voltage Standing Wave Ratio).

Flesh has a very non linear heating effect with frequency due to the fact that different molecules have very different resonance absorbtion curves and at lower frequencies is also very dependent on the size of the target. For instance at VHF a standing human looks similar to a 1.5×0.5×0.3 meter bag of salty water (go look at NRPB publications for human body absorbtion models and the significant cautions that go with them).

Also natural fibers etc used for clothe (especialy when wet) are also very suseptable to the heating effect of microwaves.

So there are one heck of a lot of details to get right to ensure people only “feel the heat” not “get burned” into a casket.

Will β€’ March 16, 2012 9:49 AM

I saw an article in Wired on this last week where they mentioned that it has a SIXTEEN HOUR bootup time.

Sounds like the tech just isn’t there yet.

Captain Obvious β€’ March 16, 2012 9:58 AM

This thing was a joke when it first was considered. Opponents don’t like it for the potential harm, the military doesn’t like it because it doesn’t do enough harm.

In demonstrations they showed years ago it could be thwarted using plywood or a mattress as a shield.

It requires line of sight, but can only work at a distance to prevent mobbing. The realistic applications are quite limited…maybe for targeting an occupied park?

NobodySpecial β€’ March 16, 2012 10:07 AM

The British claim to have a much larger orbital heat-ray deployed and hope to demonstrate it for a couple of days in August.

llewelly β€’ March 16, 2012 10:12 AM

“”In contrast, microwave frequency is around one gigahertz, which moves faster and penetrates deeper”

Moves faster??? ”

gigahertz makes everything faster. It’s Moore’s law!

Adam β€’ March 16, 2012 10:27 AM

Perhaps less lethal is more accurate. Tasers, pepper spray, rubber bullets / beanbags, water cannons etc. are also often called non-lethal but its not hard to envisage ways they could kill and have killed.

I suppose non lethal weapons are still better than the alternative of bullets and batons when dealing with a large angry mob.

I wonder what this heat ray does to petrol bombs or any pressurized containers someone in the crowd might have the misfortune to be holding.

Nick P β€’ March 16, 2012 10:45 AM

@ Bruce

If you’re talking ADS, it’s old news.

I can’t find my original article from 2003-2005 online. In that article, a Popular Science employee gets hit by the weapon. He describes a spot of heat on his body that get’s so unbearably hot that he moves without wanting to. He said they were testing it on special forces types and the record was 2-3 seconds. Hence, it makes you feel tons of pain, forces you to move and supposedly only causes superficial damage.

As they’ve been testing it since 2003, it’s not the mystery you make it seem. It might actually be one of the safest if only b/c they have so much data on it before deployment. Heck, I thought they were already using it in the field with the program being this old.

Clive Robinson β€’ March 16, 2012 12:13 PM

@ Nick P,

I’ve got a few minutes spare so I’ll throw some numbers around.

First of the wavelength, the article says 95GHz so,

300/95000=0.003157894meters or ~3.2mm

The usuall aprox for depth of field penetration into an absorber is 0.5-0.75 wavelengths so,


Which agrees fairly well with that quoted in the article Bruce links to

Now the gain of the antenna, let’s assume the flat panels shown in the photos are parabolic equivalent and look to be about 2.25m in diameter. So from,

Gain = (Pie . Diam / wavelength)^2 . Eg


Pie = 3.1415926
Eg = efficiency ~ 0.8 for an offset feed out of beam

Gives ~ 4.01E11 or 116dbi

Which is fairly impressive but not as much as -3dB beam width,

Theta = 70 Wavelength / Diam

Gives ~0.01 degrees

Which at 600meters gives 0.1meters spread or a beam about 2.5m diameter.

So on the assumption a human target is 1.5m by 0.5m equivalent target or 0.75 square meters the half power beam at 2.5m diameter has an radiuss of 1.25m and an area of Pie.r^2 ~= 4 square meters so aproximatly 1/5th of the power in the main part of the beam warms up the target so about 10% of the RF energy out of the feedline output…

Now on the assumption the body can conduct away about 50% of the incident energy on the front you would have to heat a naked person from abient by about 20C for it to be painfull, as this happens in around 3 secs you’ld be looking at ~30KW liter. So 0.75 square meters by 2mm gives about 1.5 liter meaning you’ld need ~450KW into the antenna. Hmm that sounds a little excessive…

Dave β€’ March 16, 2012 2:45 PM

Ayn Rand’s version was called “Project X” … granted, that fictional device was acoustic in nature, but the warning remains…

Joe β€’ March 16, 2012 4:43 PM

What about using a narrow bandwidth ray at a resonance frequency of C4. Might that cause suicide bombers to have a premature explosion.

MikeA β€’ March 16, 2012 5:52 PM

The acoustic version I recall was French, and basically a big low-frequency whistle/foghorn, and not intended to be non-lethal. But, unlike Rand’s was real.

SnallaBolaget β€’ March 16, 2012 7:48 PM

(The ADS was deployed in 2010)
(On September 22, 2004, Raytheon was granted an FCC license)
(There was also one laboratory accident in 1999 that resulted in a small second-degree burn.)

Nick Leverton β€’ March 16, 2012 9:03 PM

The British claim to have a much larger orbital heat-ray deployed and hope to demonstrate it for a couple of days in August.

But you’ll have to be ready, or you’ll miss it

Nick P β€’ March 16, 2012 10:28 PM

@ SnallaBolaget

That’s what I was saying. In a rare happening, he missed it by over a decade.

joe β€’ March 17, 2012 12:12 AM

What about a narrow band ray at a resonance frequency of C4. Would that cause suicide bombers to explode prematurely?

tomm β€’ March 17, 2012 1:03 AM

After being frisked at an airport instead of subject myself to a full-body scanner, I read up on millimeter wave scanners, which work at exactly the same frequency (95 Ghz) as the Active Denial System, aka the “Heat Ray”. I significantly expanded the wikipedia effects section, which I think is worth a read if anyone wants more details:

I have 4 key takeaways from my research:

1) There’s now a video of it in action on a test group, which is very instructive of the effects:

2) Anyone that ignores the heat and thinks they can take it, or is incapacitated and can’t flee the area, gets 2nd degree burns+, with blisters covering all exposed flesh. This happened to one serviceman during testing, and he was hospitalized for 2 days with burns on both legs.
“Airman injured in heat-beam test”:

3) It’s unknown if 95 GHz hits any resonance frequencies in any DNA or RNA strands in the human body; if it does, it could unzip them and be a large cancer risk. This has been clearly shown in the THz range, though evidence (and basic knowledge) is lacking in the fractional THz range (95 Ghz ~= 0.1 THz, of course)

4) On the plus side, the “heat ray” at 95 GHz only penetrates to about 1/64″, so your internal organs and gonads won’t be affected, just your skin (unlike microwave ovens at 2.45 GHz, which penetrate to about 2/3″, as anyone that’s tried to cook a roast in a microwave knows). Any cancer that forms as a result of exposure (or overexposure, as any untoward effects are defined) is easier to excise.

Once more step β€’ March 17, 2012 7:01 AM

the act of inflicting excruciating pain, as punishment or revenge, as a means of getting a confession or information, or for sheer cruelty.

The definition of torture.

Doesn’t include “as a means of getting someone to do what you want”, which here would be moving away, but I’d say it should be.

Pedants would say “but they’ll stop if you go away”. Well yes, as they’d stop once you told them what you know, I guess.

Mark β€’ March 17, 2012 10:00 AM

The act of inflicting pain or injury, as a means of getting people to stop attacking you, or thowing s#%t.

The definition of fighting back. Try being a cop or a soldier and maybe you’ll get it.

Sure β€’ March 17, 2012 1:24 PM

You mean, those people whose job it is to kill (soldiers) or beat up (cops) unamred people ?

Try being a poor guy in the street instead of one of those body armor wearing thugs.

Jarda β€’ March 17, 2012 5:12 PM

When was the last American invention, which somehow didn’t relate to war, killing, hurting, incapacitating, snooping…. Feels like centuries ago.

Clive Robinson β€’ March 18, 2012 12:49 AM

@ Jarda,

When was the last American invention…

Actualy most of the “inventions” for death and destruction did not originate in the US, but other places. The US is one of the few places in the world where you can get money in quite large amounts for developing “death rays” and even “nonlethal death rays”.

But if you want to have a more general musing think just,

“When was the last American invention”

Some commentators would have you believe it was “condensed milk”. Whilst not true a large part of the world views the US as “idea stealers”, an opinion to which there is plenty of supporting evidence. But few actually dig down and ask why?

Firstly you need to understand that at the time of the start of industrialisation the US was a wide open place with ressources for the taking, which ment that effectivly it was what we would these days call “A green fields site” it was unencombered by laws, rules or the social preasures that arise from population density. Unlike other parts of the world such as Europe.

This had a cultural effect that was a strong differentiator to that of Europe, the US has in the past been a place where product development by rapid incrimental steps was easily possible. That is it’s in part cultural, in that in the US it used to be that “having a go at doing something” was more important than actually succeeding, that is the failing of an idea was generally not looked on with shame as it is in other cultures. Thus leasons learned could be carried forwards so there was more of a “try and try again untill you succeed” mentality in the US.

This was engendered by the fact that in a “green fields” environment it was much easier for people to take chances and cut corners etc as a “means to an end” thus force multipliers such as explosives were more commonly used than other emergent industrialised nations. Likewise there were few “teardown costs” caused by preassure on land or other resources, you just moved to the next bit of “green field” and started again. It is very easy to miss or missunderstand the economic advantage of apparently endless “green field development”, and the effect that has on the development of “force multipliers”.

One inhibition on rapid incremental development is “setup costs” and it is mainly a manpower limitation in that there is only so much dirt a person can dig in a day, and only so many diggers you can have in one place before they start interfering with each others productivity. This encoraged various forms of mechanisation which started the development of force multipliers and work processes. Neither were US ideas they had been around in Europe for a century or so before hand but were too crude to offer much advantage in a resource limited environment.

Once a trend for force multipliers starts it is almost impossible to stop, it’s like a hurricane, as long as it has the resources to drive it, it will grow and grow and become rapidly more powerful. Men truly can become an “army of one”. But almost oddly having more power enables for greater efficiency of resources as well as utilisation. For instance it alows for vertical development of land well above just a half dozen floors and this has other force multipler led efficiencies (transportation, giving more efficient social care, education and entertainment etc)

Thus the US started to lead on industrialisation because of force multipliers, this ment that manufacturing was less expensive in of it’s self let alone the significant additional help of “green field development”.

But this gave rise to another problem, how do you hang onto your success?

And this is one of the main parts of the problem IP protection by patent etc and a US legal system that is based on “each side pays their own costs”.

In most parts of the world patents are limited in that you can only patent inventions that give rise to tangible physical items, not ideas and processes and methods.

Thus in the US money is not made in traditional ideas, but taking ideas to market and all the processses involved, and it is the ideas behind the processes that are more highly regarded as money makers than the ideas behind a new product. Thus the US patent system alows for their protection (hence mathmatical and software patents).

The problem with patents currently is they form legal cartels, and as is well known cartels are not known for inovation but price fixing.

Thus the US used to be a good place to take an original idea and get it developed into a product (there are much better places these days). Thus the consumer saw US made not their home nation made products and this started the idea that the US Stole Ideas. What further ingrained it was the US patent system, it acts not just to form cartels but as a trade barrier and is one of the underlying features of modern “trade wars” between nations.

I could go on about the background but I won’t, in part because my post is already too long, but mainly because I hope it will give you the seed to go and think about the problem yourself.

And this is important becausse the US has started to find that their IP protectionism has back fired on it, industrialisation has moved to other green field sites and will continue to do so just to avoid IP protectionism as well as find cheap labour. The US has also discovered that basic resources such as minerals are increasingly nolonger available to them at prices that are adventageous, and as in past times where the US used resource control against other nations it is finding that this is now being turned against it. Which means that the ultimate resource “energy” is the next main battle ground. And here the US is behaving much as Europe did with resource issues a couple of centuries ago, it’s stuck in the past and doesn’t have a “green fields” way out of the problem.

The solution is frightening to see develop and I would urge people to go and have a look at the history of “water right”. Because one way the US can maintain it’s position is by denying other nations the ability to develop their own energy resources by nuclear technology and using over whelming force of arms to control other energy resources at source. And this is not a game unique to the US Russia has proved it is quite happy to “turn the tap off” on energy dependent satellite nations in order to effect direct political influance/control.

PeterV β€’ March 18, 2012 6:36 AM

However, after the juice runs out the perps will return. And then you have to rely on the simple .50 cal again… Or am I being too old-fashioned now :-).

Fnord β€’ March 20, 2012 9:30 PM

When was the last time anything was invented anywhere that wasn’t applied, somehow, to warfare, hurting, or snooping?

Increase crop yields, and SOMEBODY is going to use it to support more soldiers. Invent a more efficient engine, and somebody’s going to notice you can use it to transport soldiers with less fuel. Invent a cheap way to launch things into space, and somebody’s going to use it to launch spy satellites.

Paul β€’ March 23, 2012 8:27 AM

So the military now has a pain ray, which does no long term damage (or a level of damage that can be handwaved away). When this tech is mature, it may replace waterboarding and stress positions – after all, its just a ‘nonlethal weapon used to control prisoners’.

Leave a comment


Allowed HTML <a href="URL"> • <em> <cite> <i> • <strong> <b> • <sub> <sup> • <ul> <ol> <li> • <blockquote> <pre> Markdown Extra syntax via

Sidebar photo of Bruce Schneier by Joe MacInnis.