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Newly Declassified Window Film Keeps Out Snoops
An anonymous reader writes to describe a newly declassified window film from CPFilms Inc. that could give war drivers fits. Scientific American has the story, which includes a rather dismissive comment by Bruce Schneier.
"Once manufactured under an exclusive contract with the US government, this recently declassified window film is now available to the public. But don't expect to see it on store shelves anytime soon. Currently, it's only available directly from the manufacturer, and at prices that will likely make it prohibitive for all but the wealthiest home owners.
The two-millimeter-thick coating can block Wi-Fi signals, cell phone transmissions, even the near-infrared, yet is almost transparent... It can keep signals in (preventing attempts to spy on electronic communications) or out, minimizing radio interference and even the fabled electronics-destroying electromagnetic pulse generated by a nuclear blast."
You should get rid of it anyway. http://people.csail.mit.edu/rahimi/helmet/
They can, but you can use foil there. In fact if you have a modern enough house it is likely to have foil in the external wall insulation. Same for the roof. It is also trivial to retrofit (you can just lay it under a plasterboard.
As a result the doors and the windows remain the sole way in and out for the radiowaves. While special films like the one described in the article can deliver a nearly perfect insulation, they are not necessary.
If what you are bothered about are script kiddies driving down the street (or in your neigbour's basement) or interference from your neigbour's AP standard K-glass (or similar IR reflective type) will do. In my previous company we did a survey prior to moving into a new office and the drops was by more than 30db in the 802.11b/g band (in layman terms from 95% "quality" to sub 5%). In fact the drop from K-glass was more than the drop through a concrete floor covered by a steel plated grounded raised floor.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
http://www.sigsegv.cx/
Can't blame the editors. The claim regarding resistance to EMP is a direct quote from (the ad copy embedded in the middle of) TFA. Morever, what TFA has to say about the film and EMP is that it is "capable of minimizing radio interference and even...EMP." They don't say block it, they say minimize it. The effective frequency range of the film is 10 Hz. up to "just shy of visible light" so I'd say they at least have a shot at it.
Now, EMP is what, again? Oh, yeah, Electro-Magnetic Pulse. Put another way, a really, really strong blast of RF interference. Anything that can completely block cell phone and wifi signals will at least somewhat hold back EMP. TFA goes on to say that one of the things that makes the film so effective is that it's part of a completely package. The film is only one component of what you're buying. Sounds like they probably retrofit the building with some kind of Faraday cage-like gear.
EMP doesn't melt plastic, it fry's electronics. Well, if you were so close to the hypocenter that the EMP could melt a 2 mm plastic film on the window, that would be the least of your problems, because if you didn't get vaporized at about the same time, the shockwave that arrived shortly thereafter would blow you, the window, and maybe the wall to the other side of the room.
The EMP they are trying to guard against is the high air burst kind (think huge warhead detonated in LEO over the US east coast) which is intended to take down electrical grids, telephone networks, and as much of everything else electronic as it can. A lot of Soviet (and presumably now Russian) scenarios included such an air burst as an early shot. Get one of those in position undetected and detonate it and you're then in a position to do a couple of things, such as:
If you have your buildings protected to the best possible extent by EMP shielding such as that stuff, it might allow you to launch in such a scenario before the other side does. You'd pretty much have to, because the EMP would fry the recon sats that would normally tell you if they were launching or not. You'd have to assume they were.
If it were effective, it would still be classified.
. kaya-optics.com/images/kodak_1_s.jpg&imgrefurl=htt p://www.kaya-optics.com/products/applications.shtm l&h=142&w=118&sz=23&hl=en&start=4&tbnid=KD3TcOf3Id c-bM:&tbnh=94&tbnw=78&prev=/images%3Fq%3DIR%2Bphot os%2Bsunglasses%2Btinted%2Bwindow%26gbv%3D2%26svnu m%3D10%26hl%3Den
Not always. Many things that were classified are no longer classified because they became common knowledge and no longer required protection. Some examples are encryption standards, Nuclear basics, some radio modulation techniques, some CPU's, some radio frequencies, and much data from WWII. Even some of the SR71 information is no longer classified.
The fact a window tinting film can have a metalized film that blocks RF is now common knowledge. Others have stumbled upon the fact. Offices with metalic colors such as bronze, copper or stainless, have had problems with cell and pager coverage. GPS users have had reception problems in some vehicles. Many films are designed to reduce IR transmission to keep the heat out. With all that general knowledge, having a classified film with these properties is a moot point.
Just because it is declassified does not make it ineffective. The stealth fighter is still a low radar profile item.
It was classified when the film was used on the cockpit windows of stealth fighters to prevent radar reflections from entering the cockpit and having a retro-reflection back to the radar source. It's now common knowledge the stealth fighters have RF screens over things like Jet intakes and conductive films over windows so the plane's cavities do not reflect a signal back to the direction it came from. This lack of a reflection back to the source is what makes a stealth plane invisable to radar. Very little signal returns. All reflections are sent off to an angle, not back to the source. It's no longer a secret, so the film tech is now declassified.
If you don't want to spend big bucks for the official military product, visit your local car window tinting shop. Ask for a film that keeps out the heat and has a a nice metalic tint. Ask for samples. Take them outside and lay them on your GPS while watching signal strength. Pick from the ones that kill the GPS reception. Now you have one that blocks far IR, maybe near IR and radio. If you need to block near IR, take a IR modified webcam and see if it is transparant in the near IR. Most non-metalic window tints are water clear in the near IR. An IR camera sees through them like ordinary window glass.
Sample photos of IR and sunglasses and other materials. Caution, fabric photo may not be safe for work.
http://images.google.com/imgres?imgurl=http://www
The truth shall set you free!
Several places make "magenetic paint" you can buy it at home depot. Paint your outer walls and ground it (copper strip going to water pipe below painted over works great. (grounding leeches off EM fields so help reduce reflections and overall background noise.)
voila, no wifi or cellular.
Using a special expensive window film is silly, replace your screens with aluminum screens and magically they also no longer pass RF energy.
I get a kick out of all this "new" stuff coming out. Anyone that owns a home that was re-sided in the 70's and 80's typically has aluminum siding and aluminum screens and therefore is mostly living in a faraday cage. (except roof)
Most of the new metalized layers on new construction materials (if any is used) dont block RF worth a darn. I tried them all at new construction sites and none were as effective as good old aluminum sheeting and screening.
Do not look at laser with remaining good eye.