Anti Wi-Fi paint

[Quantos]

Seems like this could cause problems within your home. I wonder how much testing has been done on it.

How could living in a faraday cage cause problems?

[BC_Programmer]

And ...
Windows,
Doors,
Vents,
Trap doors.
Electrical outlets, light fixtures, wallplates for Ehternet.
(The opening is larger enough to pass microwaves.)

But there is another technology. You just run a wire from each computer in the same room. Just a single wire. No hub, no Ethernet. It is wired microwave. Not new. Just nobody likes it.

An yet another technology is advanced infra red.
http://news.cnet.com/Short-Take-IBM-to-ship-infrared-networking-tech/2110-1033_3-226126.html
Yes, old story. But so is the technology in the topic.

the problem with assuming the paint needs to cover everything is that people forget that radio waves travel in a straight line.


vents and so forth on the ceiling are unlikely to provide anybody except baloonists a straight-line path to your Wireless access point. And the areas where you can get a signal outside the house at reasonable altitudes are so small as to be undetectable. And you could always secure it with WPA or WPA2 as well; I'm sure you'd notice somebody sitting in your rose bushes for a few days trying to crack your encryption. The Paint would also make such encryption nearly impossible anyway- it relies on intercepting signals sent from and to other devices; chances are it will be nearly impossible to find a location that has a straight-line path to both the access point and one of the connected wireless devices.

[Geek-9pm]

...straight-line path to your Wireless access point..

At close range any opening is leak. It is not light, it is a radio emission orders of magnitude longer the a light wave. In fact, a small opening disburses the radiation. A light switch  is about the right size to do this.
Somebody might want to make this a science project at school. Get a handy talkie and a big sheet of aluminum and a homemade field strength meter.
You will find the sheet blocks the emission, a light switch size opening lets it through, and not line of sight.

[BC_Programmer]

It's electromagnetic radiation. it travels in a straight line.

Next you'll say it travels at a different speed every third tuesday...

[Geek-9pm]

It's electromagnetic radiation. it travels in a straight line.

Next you'll say it travels at a different speed every third tuesday...

Read my post again until you understand it. Please.
When a radio wave comes the a large metal sheet with a hole in ti, the hole disburses the emission. Do I need to draw you a picture? It is too hard to visualize? The point was that an opening the size of a light switch will send the  the radiation in a broad beam. (At microwave frequencies.)

[Quantos]

Read my post again until you understand it. Please.
When a radio wave comes the a large metal sheet with a hole in ti, the hole disburses the emission. Do I need to draw you a picture? It is too hard to visualize? The point was that an opening the size of a light switch will send the  the radiation in a broad beam. (At microwave frequencies.)

So you have a microwave transmitter in your router and laptop?

I've been involved in setting up a microwave transmitter, and they do indeed need line of site to operate.

[Geek-9pm]

I've been involved in setting up a microwave transmitter, and they do indeed need line of site to operate.

Then you should know about aperture dispersion and aperture coupling. Was that not in your study guide when you got your Radio Engineer license?
These relate to methods used in antenna design, and can make the microwave beam more narrow, when used as part of a design. However, a random aperture  in a nearby conductive  sheet becomes a security issue. Like an opening in a wall with conductive paint,

 A light switch hole is a size that will pass microwaves used  the 802.11  a/b specs. But you can eliminate the problem by painting the inside of the switch plate.

Of course, we are not talking about antenna design in this topic. We are talking about using paint to eliminate radiation from the router or Desktop or Laptop from escaping from the room and presenting an opportunity for someone in the next room eavesdropping on the private network.

If there is an opening in the wall about the size of a light switch, it becomes a form of aperture coupling and will disperse into a somewhat wider beam. This is not an issue if the spy is 200 yards away. But it is an issue if the spy is just two doors down on the same floor.