Schneier on Security

Clive Robinson • 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,

1.6-2.4mm

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

where,

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…

Clive Robinson • 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.