Microwave stealing my Wifi signal

[tutrakan4e]

So this is what I've noticed:

When I get back home in the evening I like to get my phone that is connected to my Wifi network and watch youtube videos in the kitchen. Nothing special.

But what's really interesting is that when I turn the microwave on the phone loses connection and the video stops. As soon as the microwave has finished heating the food up the phone reconnects to the router and the video continues.

I'm sure this is basic physics but it's really interesting and I've decided to share it with you guys.

[Tex_NL]

Classic EM interference. Your microwave oven simple puts out enough energy at precisely the correct frequency to block your wifi signal.

Microwave oven

Microwave ovens operate by emitting a very high power signal in the 2.4 GHz band. Older devices have poor shielding[citation needed], and often emit a very "dirty" signal over the entire 2.4 GHz band.

This can cause considerable difficulties to Wi-Fi and video[citation needed] transmission, resulting in reduced range or complete blocking of the signal.

The IEEE 802.11 committee that developed the Wi-Fi specification conducted an extensive investigation into the interference potential of microwave ovens. A typical microwave oven uses a self-oscillating vacuum power tube called a magnetron and a high voltage power supply with a half wave rectifier (often with voltage doubling) and no DC filtering. This produces an RF pulse train with a duty cycle below 50% as the tube is completely off for half of every AC mains cycle: 8.33 ms in 60 Hz countries and 10 ms in 50 Hz countries.

This property gave rise to a Wi-Fi "microwave oven interference robustness" mode that segments larger data frames into fragments each small enough to fit into the oven's "off" periods.

The 802.11 committee also found that although the instantaneous frequency of a microwave oven magnetron varies widely over each half AC cycle with the instantaneous supply voltage, at any instant it is relatively coherent, i.e., it occupies only a narrow bandwidth.[3] The 802.11a/g signal is inherently robust against such interference because it uses OFDM with error correction information interleaved across the carriers; as long as only a few carriers are wiped out by strong narrow band interference, the information in them can be regenerated by the error correcting code from the carriers that do get through.

http://en.wikipedia.org/wiki/Electromagnetic_interference_at_2.4_GHz#Microwave_oven

[Dkmdlb]

Wow. I thought this was going to be one of those nonsense crackpot mental illness posts and it turned out to be science. Learning is fun!

[goldenpeach]

I though this XKCD comic was quite related to the subject

In case you wonder, the title text is ("Cheater!" "Hey, gaming on wifi? You have only yourself to blame.")

Edited November 8, 2014 by goldenpeach

[ZedNova]

Yeah, happens to me all the time. interference Doesn't kick in till the microwave is on for more than a minute though.

[K^2]

Usually, interference from microwave is kind of a bad sign. There'll always be some, but if it's really so bad that you can't use an otherwise good wi-fi connection when microwave is running, there might be significant leaks, and that's bad.

As a short-term solution, I wouldn't stand close to that microwave when it's running. In long term, I'd consider getting a new one.

[jwenting]

or maybe you're just not having enough electrical power, and turning on the microwave causes the power flowing to your router to decrease, causing in turn the WiFi signal strength to drop.

You'd likely also notice things like lights dimming if that's the case (and yes, I've had that where I grew up years and years ago, we couldn't run the oven together with the television or we'd get a brownout, the lights would go out, heating would fail, etc.).

[GigaG]

On my BGN network, I've used my iPad 3 and (less often) my Phone 5S (and my former 4S, probably) right next to the microwave and I don't have major issues. I don't think I'm on 5GHz (the 4S can't use 5GHz anyways. and I think we had our current router before I got my iPhone 5S. though I may be wrong.) Do some microwave ovens contain their microwave radiation better than others? Do some microwave ovens have frequencies that don't interfere with Wi-Fi? Or am I just lucky?

[Boomerang]

or maybe you're just not having enough electrical power, and turning on the microwave causes the power flowing to your router to decrease, causing in turn the WiFi signal strength to drop.

You'd likely also notice things like lights dimming if that's the case (and yes, I've had that where I grew up years and years ago, we couldn't run the oven together with the television or we'd get a brownout, the lights would go out, heating would fail, etc.).

Can confirm, from having lived in a house with scary-old wiring. God forbid someone turn a coffeepot on when the microwave *and* washing machine were running.

[K^2]

That blew out my circuit breaker every time in the old house, resulting in the trip to the basement. Eventually, my wife learned to connect the coffee pot to another circuit.

But yeah, that would have other side-effects. If all that happens is a wi-fi drop, a leak is far more likely.

[WestAir]

K^2, why stand away from it if it's only outputting non ionizing EMR?

[K^2]

K^2, why stand away from it if it's only outputting non ionizing EMR?

Non-ionizing just means that it won't give you cancer. Doesn't mean it can't hurt you. It is designed specifically to cook your food from the inside. What do you think a leak will do to you?

Essentially, powerful microwave source can cause internal burns which you might or might not feel right away. It's extremely uncommon, and would require a number of unfortunate coincidences on top of the microwave's shielding failure, but it is a potential risk.

[Nuke]

i dont even own a microwave, it ruins the food.

[vger]

Non-ionizing just means that it won't give you cancer. Doesn't mean it can't hurt you. It is designed specifically to cook your food from the inside. What do you think a leak will do to you?

Essentially, powerful microwave source can cause internal burns which you might or might not feel right away. It's extremely uncommon, and would require a number of unfortunate coincidences on top of the microwave's shielding failure, but it is a potential risk.

It's best to stay away from microwaves when they're operating anyway. Even with a leak, the rays don't reach very far before they become negligible.

[ZedNova]

I've heard some people get past this issue by changing their router settings, you can modify the frequency a little bit by changing the channel. Though unless your MW is interfering with a very specific frequency i doubt it will work.

The other way to circumvent the problem is to get a 5ghz router, but older devices might not work with it.

I've noticed the microwave will also interfere with digital over-the-air TV signals.

And guys, i'm pretty sure a microwave with no shielding whatsoever will only AT BEST cause a warming sensation on the surface of your skin. Unless you stand in front of it for days on end at full blast i doubt it's gonna hurt you at all.

Edited November 9, 2014 by ZedNova

[WestAir]

Non-ionizing just means that it won't give you cancer. Doesn't mean it can't hurt you. It is specifically to cook your food from the inside. What do you think a leak will do to you?

Essentially, powerful microwave source can cause internal burns which you might or might not feel right away. It's extremely uncommon, and would require a number of unfortunate coincidences on top of the microwave's shielding failure, but it is a potential risk.

I figured the only risk was from burns but I assumed the damage would be immediately evident: "Oh god I'm burning. Run away!"

[magnemoe]

Usually, interference from microwave is kind of a bad sign. There'll always be some, but if it's really so bad that you can't use an otherwise good wi-fi connection when microwave is running, there might be significant leaks, and that's bad.

As a short-term solution, I wouldn't stand close to that microwave when it's running. In long term, I'd consider getting a new one.

Note that the power requirements to jam an wifi signal is way less than the leak from an microwave oven who works perfectly.

http://en.wikipedia.org/wiki/DBm

Yes an microwave oven who don't close well would be dangerous, not one watt who is the legal noise level. Other electrical stuff can make more noise.

Had an office where the tram killed all mobile phones on cold days then it passed. Guess it was sparks from the power line to the tram collector who generated the radio noise.

[K^2]

These are legal limits, but it has not been the "typical" strength in my experience. If I can get strong signal from Wi-Fi to begin with, I might experience quality drop, but not a total loss of connection. Keep in mind that it isn't just about power ratios. A receiver can operate in pretty bad S/N with a lower rate.

But yeah, it certainly doesn't imply dangerous levels of RF. There are plenty of harmless sources that can kill your Wi-Fi. And even if microwave causes that, it doesn't automatically mean that it is dangerous.

All I'm saying is that in my experience, if the MW oven was functioning well, interference was not that bad. And the only time I've seen a MW oven that flat-out kills Wi-Fi has been with a significant leak due to mechanical damage of the oven.

Not standing close to a microwave that is causing that much interference, you know, just in case, just seems like a good idea.