Wallpaper That Blocks Wi-Fi | Hacker News Reader

Wallpaper That Blocks Wi-Fi

blogs.wsj.com

20 pointsnikunjk26 comments

Before clicking the link I thought it was a malformed computer desktop wallpaper exploiting some kind flaw in the operating system and using it to block the computer from connecting via Wi-Fi.

Would have been very much cooler, would it not?

I thought along similar lines, but with some special texture that made monitors emit some kind of wifi-jamming RF :)

"as well as those who, for health reasons, simply want to shield themselves from as many electromagnetic waves as possible"

Is anyone really still concerned that electromagnetic waves in the cell-phone range are harmful?

Yes there are, but you won't find them here or on my websites.

This reply is just for the search-engine people.

(http://www.who.int/mediacentre/factsheets/fs193/en/)

> To date, research does not suggest any consistent evidence of adverse health effects from exposure to radiofrequency fields at levels below those that cause tissue heating. Further, research has not been able to provide support for a causal relationship between exposure to electromagnetic fields and self-reported symptoms, or “electromagnetic hypersensitivity”.

> The researchers concluded that biases and errors limit the strength of these conclusions and prevent a causal interpretation. Based largely on these data, IARC has classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B), a category used when a causal association is considered credible, but when chance, bias or confounding cannot be ruled out with reasonable confidence.

I'm a scientist (certified for radioactive & x-ray research) so I totally hear the point to be made regarding something not being a fact until a thorough investigation has been done on the matter. However, the fact that electromagnetic wave cause harm or may have secondary effect in some people is not that far fetched and should not be discarded as "is anyone really still concerned". We just don't have a sample size of individuals troubled by it that is sufficiently large enough to prove it. The majority of us may show no signs of harm; yet I know of at least two people that suffer from electromagnetic hypersensitivity, probably resulting from having 30 different wifi signals crossing their walls day & night for the last ten years. Indeed, I don't believe cell-phone tower signals at long range are really the cause. It's more likely to be the high concentration of wifi signals inside of apartment complexes. And even if the exposure intensity is a matter of square root with respect to distance from source, you can get significant exposure when you increase the number of source or the relative average distance you are from them. So no, electromagnetic waves is nothing to sneeze at. If you think so, why don't you go sleep every night in a tiny room with 15 wifi routers on and a couple of cell-towers directly above your head?

I'll see your anecdote and raise you another one:

A friend's downstairs neighbour regularly complained of 'electromagnetic hypersensitivity'; it got to the point where the building manager asked that my friend stop using wifi entirely. My friend switched her network to 'hidden'. The symptoms disappeared.

Of course, we shouldn't draw conclusions from anecdotal evidence. Perhaps the neighbour was only sensitive to broadcast packets containing SSIDs?

Does the neighbor also block out all the harmful EM radiation that floods from sunrise to sunset? If you want to be cruel, mention that cordless phones and microwaves emit at similar frequencies as wifi.

Cordless phones are actually by far the most powerful radiowave emitter inside a home.

"We just don't have a sample size of individuals troubled by it that is sufficiently large enough to prove it."

well yeah, then when you do find someone, you have to sort the lunatics from the real cases :)

Depending on the size/shape of the apartment, this seems like it could cause some interference issues. A hallway lined with wifi-blocking wallpaper would produce some kind of weird multimodal effects, wouldn't it?

In the new houses in my neighborhood, I see that they use some kind of 'home wrap' on the wood before insulation. I could see them installing this on the outermost walls of schools, sensitive/government offices, or other places (e.g. churches, aforementioned concert halls, hostels, etc.) between the outer walls and insulation.

However, you are correct with your comment. In some cases, though, this could be desired, e.g. a hotel that wants to provide, track, and bill for WiFi on a per-room basis.

Cheap alternative: cover the walls with thin chicken wire.

I got a better one. Use an ethernet cable.

what? is that like some sort of wifi over wires? neat.

No, it's just easier to obtain than chicken wire but has similar metal content for signal scrambling, and plastic insulation to avoid scratch damage to skin.

Unfortunately something like this is not nearly as effective as you may imagine. I spent more money than I'd like to admit a few years ago trying to shield my hi-fi stereo from all sorts of interference. I lived on Avenida Paulista with about a half dozen to a dozen massive radio and tv antennas within about a mile. No matter what trick I tried the noise was still getting through in every way imaginable.

These kind of filters are attenuators, not blocks. If you're that close to very powerful transmitters, then even reasonable attenuation is going to allow some signal through.

Yup. I learned that the hard way. The best I was able to achieve was putting power cord chokes along the entire length of the interconnects (RCA <-> RCA).

The ideal solution would be balance power amp and balanced pre-amp with XLRs carrying the audio signal. Unfortunately this would have required completely new amps.

This might be an effective solution to the "no cellphones in class" rule.

Probably the most important factor is still letting emergency bands through. Does anyone know if 911 calls go through normal cellphone channels, or if that's a dedicated channel that can be 'whitelisted' on a device like this?

It's not a device. It's metal in a wall paper.

I'd use it at home, just on exterior-facing walls. This would not only block any interference from neighbors WiFi/microwaves, but also won't let them see my WiFi traffic. Throw in a cell repeater in the wallpaper package, and it'd be perfect.

Looks a bit like a Faraday cage.

It is the same concept of a Faraday Cage.

Wouldn't this be against the law as causing interference, especially with emergency equipment (in the US)?

Or do those FCC rules only apply to devices?

Passive blocking is fine, active blocking or interference is not.

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