This was one of my first app ideas about 10 years ago. Unfortunately my microwave had a mechanical timer such that if you opened the door when it was running the microwaving would stop, and on closing again it would resume. Unbeknown to me the door had been so opened, and on closing, with my HTC Desire inside, it duely resumed.
Neat idea, though it's not a definitive test. In my experience a microwave oven cavity provides about 40dB attenuation, and it's possible to maintain an LTE connection with that sort of path loss.
Hint: If you're ever doing radio work in the field and need an instant Faraday cage a microwave oven is a good candidate. Turn the power off first to reduce the risk of accidentally irradiating your device, but leave it plugged in to get an earth connection to the shield. (This is how I know an LTE connection can be maintained in a microwave oven.)
I'll confirm this works very well for 3G (600-900MHz) although I cut the hot off the plug out of paranoia when using one this way. Some of the 4&5G bands are up above 3GHz where it won't work so well.
Since your WiFi signal, however is almost exactly the same and there are many apps that will show and record signal in dB (as described in TFA). You could measure while the door open/closed if you're really careful not to turn it on. The lithium battery fire could respond very badly to water!
Depending on your region, LTE could be using much higher frequencies. Microwave ovens use a fixed frequency and the cage is designed for that. Considering this I would say it's still an effective test.
I stumbled across this little project a few weeks back, ordered the parts (just a diode and an led), and it works. Put a bowl of water in the microwave (or dinner), turn it on, then wave the lectenna around the cracks and see where it lights up.
I originally found the lectenna by researching if it was possible to power an LED wirelessly by leeching power from a house 60Hz line. I haven't made any progress on that, so if you have ideas I'd love to hear them.
If you run a low voltage 24V DC power cable for lighting next to a 220V AC line (I'm in Europe, no idea if 120V does the same) it's quite easy to get a situation where there is enough power for LED lights to be lit even when switched off. This is why low voltage wiring (lighting, ethernet, hdmi, etc) should not be ran parallel to AC power cables.
Oscilloscopes often pick up some small voltage at 60Hz when the probe isn't connected to anything, and that voltage increases when a human touches the probe by acting as an antenna. But this is because of the scope's high input impedance(1-10MΩ); as soon as you try to power something off that, the voltage just collapse to zero.
Idk if OP is the person who wrote this, but on my device the red text about not turning the microwave on is not especially legible. I’d probably make that text a bit bigger and/or brighter. I expect most HN readers will know not to microwave a phone but you’d be surprised what people might do.
Indeed, it's generally not considered legible on any common devices: WCAG suggests to ensure suitable perceived contrast ratios [1], and there are checkers around [2], while this page's #f00 on #36393F is far from meeting those.
For the safety's sake, might be nice to also recommend to unplug the microwave oven altogether as the first step.
Actually, this is not as stupid as it seems. I was first baffled by the idea that a website can read the RSSI of the device I'm on, then I realized its probably just measuring the latency by pinging every second.
I remain in awe that we trust the very cheapest plastic under repeat load and thermal cycling to form a -40dB seal, turning 700W into 70mW. Also, it seems that the outer metal shell of the device forms an active part of the circuit, so if it isn't plugged into a grounded outlet it sits at lethal potential. Then there is beryllium oxide in the thing...
I kind of doubt an independent inventor could bring this to market with today's startup climate.
> "I kind of doubt an independent inventor could bring this to market with today's startup climate."
Especially the kind of inventor who created microwaves for experiments with reanimating frozen hamsters, cough James Lovelock.
(Tom Scott's video "I promise this story about microwaves is interesting" which includes a brief interview with James Lovelock last year at age 101 - https://www.youtube.com/watch?v=2tdiKTSdE9Y )
> I remain in awe that we trust the very cheapest plastic under repeat load and thermal cycling to form a -40dB seal, turning 700W into 70mW
It's the metal grid in the window (with holes smaller than the wavelength of the microwaves), and the metal shell of the cavity, not any "plastic." The same reason the metal grid works is why there doesn't need to be a perfect door seal. As long as as the gap is smaller than the wavelength of the microwaves, it's fine.
> Also, it seems that the outer metal shell of the device forms an active part of the circuit, so if it isn't plugged into a grounded outlet it sits at lethal potential.
The shell doesn't sink RF, it reflects it. GFCI outlets (required in many areas for kitchen outlets) trip at 5mA differential between hot and neutral. No appliance is designed to sink current into ground unless there's an electrical fault.
> Then there is beryllium oxide in the thing...
Beryllium oxide hasn't been used in microwaves for a long time, and it presents zero risk unless the magnetron is smashed.
Edit: They can interfere with WiFi because a microwave could leak a tenth of a percent of its nameplate power and it would overpower your access point by anywhere from 1x to 10x. Access points can, on certain bands, have radios up to ~1W, but 125-250mW is much more common.
It would also be completely harmless even if you were standing inches away from whatever the source of the leak was. Microwave RF energy only becomes dangerous when it is strong enough to heat up parts of your body that cannot cool themselves quickly due to having little/no bloodflow, like your eyes.
You could put a parabolic antenna on your home wifi AP and standing in that beam would expose you to more RF energy than your microwave.
I don't know why HN suddenly has a "DANGERS OF MICROWAVE OVENS!" boner this week...this is I think at least the second article on the subject of the 'dangers' of microwave ovens.
Regarding "the door gap is a long line" - that would be relevant if the beam were aimed parallel (or close to parallel) with the gap...
You would need to take your access point and wave it all around various directions in the space around the microwave. The “leak” could occur in a direction that doesn’t have significant signal. Might be a better test to cook a large bowl of water, while testing your phone (outside the oven) on 2.4ghz … holding it on all sides of the oven to see if any areas degrade the signal. This testing approach isn’t that conclusive.
Agreed. I just tested with two phones and one phone timed out but the other was able to maintain a connection. That would suggest that my microwave is maybe leaking. However I'm able to use the microwave without any noticeable effects from on 2.4ghz devices.
I went ahead I tried it with a 5GHz connection (the site was practically begging me to) and it turns out my microwave blocks both 2.4 and 5 GHz signals. Pretty cool! If your wondering, it's a decade old Sunbeam that I bought for $30 so nothing special.
Brilliant. The best part of this was running into the kitchen while my girlfriend was washing dishes and watching her face as I put my phone in the microwave ;)
Or, just use an Ubertooth sniffer. From anywhere near a running microwave you should see it in the 2.4gh range. Its cool to see how some microwaves vary the frequency up and down during a cycle. It looks like a standing wave bouncing back and forth. This also explains the common office phenomena of the wifi dropping every time someone nukes something.
Ignoring impedance and assuming the microwave oven is rated at 1kW. 1kilowatt = 60dBm. A typical WiFi receivers works fine at -60dBm = 1 nanowatt. 60-(-60)=120dB, or 12 orders of magnitude. To put that into persepective, a WiFi receiver work with 1/1,000,000,000,000 the power of a 1kW microwave oven.
I needed to test behavior of an app on an actual iphone with flaky cellular and thought a microwave would be a great place to simulate this. It wasn't. The cellular connection was unaffected. Wrapping the phone in aluminum foil killed the signal enough though.
> 1. Put phone on 2.4ghz wifi (5GHZ WILL NOT WORK!)
Might be nice to expand on "will not work". Wouldn't 5 GHz Wi-Fi failing to connect show that it's even better at blocking, and would easily block 2.45 GHz too? And I'd think that they should block 5 GHz too, since those meshes look quite fine, and they probably try to be extra-safe.
This thing is totally insane.
Instructions are not clear at all and the risk that someone bakes a phone in a MWO or doesn't any other harmful thing is rather high.
Please remove this post.
related question... I have a bluetooth headset (aftershokz aeropex), when my microwave is running the audio from my phone seems to get interrupted. think it also happens if just the phone is near the microwave. should I be concerned ?
You load the web page on your phone, put it in to the microwave and close the door. The microwave should be a Faraday cage preventing microwave radiation getting through. Now the phone/web page cannot contact the internet. The chart stops updating.
Unless there's a leak, then the chart continues updating while the phone is in the microwave.
Then open the door and look if it could/couldn't keep pinging the server while the door was closed.
So should I be concerned if the phone seemed to keep pinging just fine inside the Microwave? I also notice my Bluetooth headset break up if I’m near the microwave while it’s running.
You mean like infra-red from the Sun when we have homes with windows?
(A microwave is ~1 KiloWatt up close, WiFi is ~1Watt and meters away. This is like spreading fear that your house has a warm radiator which is bad because ovens use warmth to cook food).
Not only is there a massive difference in the power of a microwave oven compared to wifi, but the mechanism through which it heats food is dielectric heating [0] which does not occur in radio signals because they are not rotating fields.
This basic information is contained in the first very short paragraph of how a microwave oven works on wikipedia.
I hear these concerns in real life and as per my longer post above, I don't understand the threat model. My oven and stove can also cook meat. It's what they do. What is the actual concern? I feel I have burned myself on ovens and stoves a lot more than I have on microwaves in my life (let alone the risks in popular gas stoves etc). I am genuinely curious what is the delta and differentiating factor making microwaved mystically scary?
The only adverse effect microwaves have been found to have on humans is due to heating [1]. WiFi transmitters emit less than 1/1000 the power that a microwave oven does. Unless your cell phone starts to make you feel uncomfortably warm, I don't think you have to worry.
hanoz|3 years ago
O5vYtytb|3 years ago
femto|3 years ago
Hint: If you're ever doing radio work in the field and need an instant Faraday cage a microwave oven is a good candidate. Turn the power off first to reduce the risk of accidentally irradiating your device, but leave it plugged in to get an earth connection to the shield. (This is how I know an LTE connection can be maintained in a microwave oven.)
kurthr|3 years ago
Since your WiFi signal, however is almost exactly the same and there are many apps that will show and record signal in dB (as described in TFA). You could measure while the door open/closed if you're really careful not to turn it on. The lithium battery fire could respond very badly to water!
fmasood|3 years ago
aimor|3 years ago
https://www.nrl.navy.mil/STEM/LEctenna-Challenge/
I stumbled across this little project a few weeks back, ordered the parts (just a diode and an led), and it works. Put a bowl of water in the microwave (or dinner), turn it on, then wave the lectenna around the cracks and see where it lights up.
I originally found the lectenna by researching if it was possible to power an LED wirelessly by leeching power from a house 60Hz line. I haven't made any progress on that, so if you have ideas I'd love to hear them.
fy20|3 years ago
dhdc|3 years ago
noodlesUK|3 years ago
defanor|3 years ago
For the safety's sake, might be nice to also recommend to unplug the microwave oven altogether as the first step.
[1] https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-cont...
[2] https://contrastchecker.com/
dijonman2|3 years ago
dhdc|3 years ago
ganzuul|3 years ago
I kind of doubt an independent inventor could bring this to market with today's startup climate.
jodrellblank|3 years ago
Especially the kind of inventor who created microwaves for experiments with reanimating frozen hamsters, cough James Lovelock.
(Tom Scott's video "I promise this story about microwaves is interesting" which includes a brief interview with James Lovelock last year at age 101 - https://www.youtube.com/watch?v=2tdiKTSdE9Y )
dhdc|3 years ago
Also, unless your electrician had a catastrophic fuck up, the metal cage will never be at live voltage, with or without grounding.
KennyBlanken|3 years ago
It's the metal grid in the window (with holes smaller than the wavelength of the microwaves), and the metal shell of the cavity, not any "plastic." The same reason the metal grid works is why there doesn't need to be a perfect door seal. As long as as the gap is smaller than the wavelength of the microwaves, it's fine.
> Also, it seems that the outer metal shell of the device forms an active part of the circuit, so if it isn't plugged into a grounded outlet it sits at lethal potential.
The shell doesn't sink RF, it reflects it. GFCI outlets (required in many areas for kitchen outlets) trip at 5mA differential between hot and neutral. No appliance is designed to sink current into ground unless there's an electrical fault.
> Then there is beryllium oxide in the thing...
Beryllium oxide hasn't been used in microwaves for a long time, and it presents zero risk unless the magnetron is smashed.
Recommended reading for you:
https://www.dannyguo.com/blog/my-seatbelt-rule-for-judgment/
https://www.psychologytoday.com/us/basics/dunning-kruger-eff...
Edit: They can interfere with WiFi because a microwave could leak a tenth of a percent of its nameplate power and it would overpower your access point by anywhere from 1x to 10x. Access points can, on certain bands, have radios up to ~1W, but 125-250mW is much more common.
It would also be completely harmless even if you were standing inches away from whatever the source of the leak was. Microwave RF energy only becomes dangerous when it is strong enough to heat up parts of your body that cannot cool themselves quickly due to having little/no bloodflow, like your eyes.
You could put a parabolic antenna on your home wifi AP and standing in that beam would expose you to more RF energy than your microwave.
I don't know why HN suddenly has a "DANGERS OF MICROWAVE OVENS!" boner this week...this is I think at least the second article on the subject of the 'dangers' of microwave ovens.
Regarding "the door gap is a long line" - that would be relevant if the beam were aimed parallel (or close to parallel) with the gap...
nullrouten|3 years ago
gruez|3 years ago
Agreed. I just tested with two phones and one phone timed out but the other was able to maintain a connection. That would suggest that my microwave is maybe leaking. However I'm able to use the microwave without any noticeable effects from on 2.4ghz devices.
dhdc|3 years ago
aimor|3 years ago
I went ahead I tried it with a 5GHz connection (the site was practically begging me to) and it turns out my microwave blocks both 2.4 and 5 GHz signals. Pretty cool! If your wondering, it's a decade old Sunbeam that I bought for $30 so nothing special.
https://ibb.co/JFcZp9H
noduerme|3 years ago
sandworm101|3 years ago
https://youtu.be/DCYrrNQc3lM https://youtu.be/6N3P842Nay8
Whether your phone can connect from inside is not a great standard. Your phone's antenna is maybe 1/100,000 the power of a microwave oven magnetron.
dhdc|3 years ago
davidmurdoch|3 years ago
tonymet|3 years ago
xattt|3 years ago
mateo1|3 years ago
defanor|3 years ago
Might be nice to expand on "will not work". Wouldn't 5 GHz Wi-Fi failing to connect show that it's even better at blocking, and would easily block 2.45 GHz too? And I'd think that they should block 5 GHz too, since those meshes look quite fine, and they probably try to be extra-safe.
dhdc|3 years ago
However I do agree that it's probably still gonna work because the faraday cages on microwaves are always overkill (even the cheap ones).
unknown|3 years ago
[deleted]
dzhiurgis|3 years ago
exac|3 years ago
olx_designer|3 years ago
janci|3 years ago
bgro|3 years ago
It’s interesting the browser can get access to this information with no prompts
notorandit|3 years ago
verve_rat|3 years ago
fauria|3 years ago
dzhiurgis|3 years ago
But one could also use fridge for this test.
ganzuul|3 years ago
Funny how kitchen stuff was thought to be women's work once.
scionthefly|3 years ago
donkeydoug|3 years ago
dhdc|3 years ago
aluminum96|3 years ago
jodrellblank|3 years ago
Unless there's a leak, then the chart continues updating while the phone is in the microwave.
Then open the door and look if it could/couldn't keep pinging the server while the door was closed.
janci|3 years ago
hedora|3 years ago
sgerenser|3 years ago
pipeline_peak|3 years ago
[deleted]
larsrc|3 years ago
jodrellblank|3 years ago
(A microwave is ~1 KiloWatt up close, WiFi is ~1Watt and meters away. This is like spreading fear that your house has a warm radiator which is bad because ovens use warmth to cook food).
tomxor|3 years ago
This basic information is contained in the first very short paragraph of how a microwave oven works on wikipedia.
[0] https://en.wikipedia.org/wiki/Dielectric_heating
NikolaNovak|3 years ago
colanderman|3 years ago
[1] https://en.wikipedia.org/wiki/Microwave#Effects_on_health