Can you call a cell phone in the microwave?
HTML-код
- Опубликовано: 8 сен 2024
- This episode is brought to you by Squarespace: www.squarespace...
Applied Hacking with Samy Kamkar: / s4myk
Do cell phones placed in a microwave still receive signals? What is the difference between microwave oven radiation and the signals used by your phone?
physicsgirl.org/
/ thephysicsgirl
/ thephysicsgirl
/ thephysicsgirl
Help us translate our videos! www.youtube.com...
More resources:
www.ncbi.nlm.ni... www.arpansa.gov...
Creator: Dianna Cowern
Editor: sefd.com , Jabril Ashe and Dianna Cowern
Thanks to ArcAttack: www.arcattack.com
Visuals: Pixabay.com and Clker.com
Music: APM and RUclips
Great, my friend watched this video with me and all she took from it is that the microwave leaks radiation.
She completely ignored where you said it was non ionizing and is currently trying to cover the microwave with "protective foil"
Thanx Diana.
I guess the good news is, after she's done entombing the microwave, she won't have enough tin foil left to make a hat.
+Diana, the Inorganic Vegan well you see it as light and feel it as heat
+daniel117100
I know. I'm just explaining the mentality of most laymen.
+Chad C. Have you seen about bananas? They are radioative, and the ionizing type too!
ShapeDoppelganger
Although not enough radiation to harm you*
lol
I am surprised. I thought microwave ovens would be much better Faraday cages than they actually turned out to be.
+Physics Videos by Eugene Khutoryansky
Actually the RF seal on a microwave is tuned to the magnetron's frequency(2.4 GHz) to reflect that frequency back to the inside of the box instead of shorting it out. It's a common technique used in radar transmitters.
It is very hard to stop microwaves from leaking through the door seals. 2.4GHz is almost like water. It leaks everywhere. The gap in the door is considerably smaller at 700 mhz than at 2.4ghz, so the seals work better at lower frequencies. Also, the transmitter for the wifi is only a few feet away. The transmitter for the cellular is miles away. The signal strengths are vastly different.
another thing is that microwaves just stop a lot of the power of the signal. that is what cooks the food. the power not the frequency. im actually surprised that the phone didnt work in all of them.
actually that makes sense why it worked in some but not others since when they were further from a cell tower or wifi router the power of the signal would be lessened thus allowing the microwave to stop it verses when you are closer it cant stop it as much.
How clean were the door seals?
Now try a banana and travel through time
For those of you who are wondering what this comment is about. It actually refers to an anime called "SteinsGate", in which a microwave acts as time-machine
+Adarsh VA Haha, I love that anime.
El Psy Congroo
Tootooroo!
I was looking for this comment
I remember dragging an HP spectrum analyzer home from work back in the 80's to do this. Most of the leakage was at the door joint. Holding the door tighter there was less leakage so I adjusted it. The internet was a university novelty then, mobile phones were mounted in the trunks of doctors and lawyers and everything over 1 GHz was a small fortune.
revisiting this months later, this is the coolest video.
Damn, I was looking for 'Psychic Girl'...this is better anyways
troll
+thedoctorzeus Psychic Girl never looks for you,for she always knows where you are.
Yeah i love physics girl
Nice work! I really liked the RF investigation. Nice shirt too ;)
+Applied Science Yeah, I thought I’d seen that logo somewhere.
Saw shirt and scrolled down hoping to see this comment. You never disappoint, Ben...
I’m wondering how much the H-Field might play a role here.
A Faraday cage, like a microwave oven, is more effective at blocking the electrical component of the electromagnetic radiation. But the magnetic component usually goes straight through the shielding unaffected.
As an avionics technician, I have performed leak tests on microwave ovens installed on aircraft. When I was performing these tests in the late 80's, EVERY microwave I tested leaked beyond acceptable limits. I was actually surprised to see microwaves that did not leak.
Shoutout for Samy's _Applied Science_ T-shirt! That's how you know he's a cool dude!
I actually work in the industry and we use microwave ovens for testing. It used to be that you could unscrew the antenna and put in a coax cable to connect to the cell hardware but external antennas disappeared. Note that in the US voice calls would use CDMA band classes 1 and 2 at 850 MHz and 1900 MHz (PCS) and sometimes the auxiliary 800MHz range. But for testing LTE data which runs in the GHz bandclasses we place the mobile UE in the microwave and run an antenna wire inside from the eNodeB. This prevents the UE from attaching to a commercial signal and our testing from affecting any users of the commercial signal. We are not allowed to bleed any RF.
Another interesting fact is that some high efficiency energy saving windows are very good at blocking LTE radio ranges. So much so that I have seen a demonstration where a mobile was placed less that two feet from from the eNodeB antenna and one of those salesman demonstration mini windows placed between them. The mobile lost communication immediately. So if you are getting a bad signal inside the house doing the "natural" thing of going to the window could be the worst choice to make.
Lead and other metals in glass and tint would be the likely culprits. Security mesh and heating elements may compound that.
The average residential wall should generally block less RF than a typical window.
Where I work the mess hall (the only place we're generally supposed to use personal phones) has a decorative aluminum grid overhead to diffuse lights and act as a ceiling, somewhat hiding ducts and whatnot. Have to go into another room (which is full of windows, lol) or outside to get useful call reception. e.e (It's a "clean" factory, so we don't just walk outside.)
With the wifi call, are your sure that the wifi was on 2.4GHz and not 5GHz? The latter is becoming more popular in a bid to find more spectrum.
+Jonathan Sawyer yes. Samy had two networks, we checked to make sure I was on the 2.4GHz network. Thanks for the question!
The subsequent question is how well would the microwave work as a faraday cage at 5GHz?
+Jonathan Sawyer if the 2.4 can enter the 5 probably can.
H I think you are probably right but if the microwave did act as a faraday cage at 700MHz anything is possible. Although the wavelength is considerably shorter at 5GHz.... I'm rambling now. I'll stick to playing at 7MHz.
+Physics Girl Have you checked the smartphone was still on the 2.'4GHz network AFTER removing it from Samy's microwave? Because it could have quickly switched to 5GHz as the 2.4GHz faded away.
i tried calling my cellphone when he was inside the microwave , i didn't get the call and the Wi-Fi was blocked , my microwave is very safe😂
however, there are also 5Ghz wifi antennas which can send the signal through smaller holes... keep an eye on those...
That doesn't necessarily follow.
That settles it. You are cooking 😋
I also did that...now my foun doesnt want to connect to wifi...what must i do please help..i even regret.my foun is Samsung j4 core
@@cezarcatalin1406 well it doesnt matter if the call signals get in as long as microwaves dontget out.
I love this video!
What are you doing here :l
@@utvikrama why must every comment by a science RUclipsr include a reply by somebody who's shocked that similar people watch each other's videos?
If anything, I find it interesting that James used his Shorts account to browse, rather than the original one or something more incognito.
(More seriously, that emoji seems to imply you're disappointed. That's even more strange than being surprised by somebody famous.)
+Physics Girl Note that Wi-Fi also uses the 5GHz band. If his wireless router supports it, the facetime call could have used 5GHz, not 2.4GHz thereby penetrating the microwave.
You get a thumbs up coz the guy is wearing an Applied Science t-shirt at 2:20 ... :D
What I appreciate most in the video is the the final discussion about bias in the observation and the sample was not homogeneous in the other characteristics :)
The issue may not be between microwaves, it may be the signal strength of the surrounding cell phone towers that your phone is communicating with. To be sure you should gather the different microwaves in the same place, and see if the results are the same.
Thank you humble man for the men-explaining. Science Girl literally said that variables such as placement of microwaves, age, cellphone towers nearby, and etc could have affected the experience... We, the people of science, all know it was just a simple demonstration, not study for a publication... I wonder if was a man you would come here and bluntly correct the demonstration and ignore the fact that the possible interference of unknown variables have been mentioned 😒🤡
instructions not clear, my phone turned into green slime
Good job pointing out the confounding variables.
+Rob Kinney I also liked that part, it was vaguely reminiscent of the summary in an actual scientific paper..
+Physics Girl I love your videos. I have a degree in physics too (from the 70s). Here's an idea for one you could host.
We all like our soda to stay fizzy once we've opened it and re-sealed it. We see tops for fizzy bottles with built in pumps in the stores that claim to keep the drink carbonated by pumping air into the bottle and pressurizing it. But they don't. The Partial Gas Law tells us that the presence of air (mostly Nitrogen and Oxygen) doesn't affect the pressure of CO2 at all no matter how much of it there is in the bottle. The CO2 ignores it completely. And the amount of CO2 in air is only 0.038% so pumping up these devices adds virtually no CO2 to your drink. And it's dissolved CO2 that makes your drink fizzy and nothing else.
So the only way to fizz up your flat drink is to add CO2 directly with a Soda Stream machine, a bit of dry ice or... I don't know. Any ideas?
I thought of submitting this idea to Mythbusters but haven't.
+Warren NZ Indeed. Pressure and solubility are independent of each other.
Charlie Franz Good point. I think the average layman assumes that the other compressed gases in the bottle will keep the CO2 dissolved because of the higher total pressure.
2:11 An applied science shirt, nice to see that around :D
Interesting to see those experiments really done. Thanks!
The reason WiFi was getting through better than cellphone signals could be that the cell tower was a lot farther away than the WiFi access point. Even though cellphone towers emit more power and have better high-gain antennas (they radiate most energy horizontally and only a little bit upwards -> poor reception in airplanes), the inverse-square law means the it is likely that a lot less less cellphone tower field intensity was arriving than WiFi field intensity.
Wait... logo from Applied Science channel ?
Yes! He's selling shirts now!
+Roshkin Ok, nice to know ;)
Yeah, Applied Science is amazing. I'm still waiting on the gecko tape. He's incredible to watch.
I can see the classic "Art of Electronics" book in the background
Yeahhh Samy !!! that guy is incredible. Btw the art of electronics spotted ;)
It's possible your iPhone used the 5 GHz wifi signals when it was in the microwave. That would explain why it still received the call when the microwave was (supposedly) blocking the 2.4 GHz signal. Also, thumbs up for the Applied Science t-shirt! :)
By pure coincindence, this video came out when I was watching Stein Gate.
Same Here I Searched.
Microwave, Cellphone, SERN.
Thanks for the information. I have read to put one's emergency radio and electronic equipment in an old microwave oven with the cord cut to protect against an EMP, and told to test it in a similar manner with the FM radio band on. Now, I have my doubts. Your test is good for people as a cheap way to check their microwave oven. Thanks. Good luck with your site.
One thought: if you considered the microwave oven as an attenuator rather than a perfect cage, you would definitely see a different picture. Your WiFi network is much closer in proximity than the nearest cellular tower and thus your reduction in signal strength might be the same, but still have enough to make it through eventhough the emitted signal strength from the system is lower.
I think a great experiment would be with 2X hack RF modules communicating and measuring signal strength at different frequencies. Give it a try and let us know what you find out. As an RF guru in the drone World, I find this stuff very fun!
Video Aerial Systems
Years ago, I powered up a radar detector with a power adapter and tested to see if it would pick up a signal from the microwave. It did. It showed up as X band, which was around 10 GHz.
Explains why I turn green when I get angry and wake up naked.
Do you wake up angry?
One important variable not accounted for is fading. RF signals that travel through the air experience significant reflections off the ground/houses/walls/people/furniture/etc. These reflections creating interference patterns as the reflected signals add and subtract and these patterns change dynamically as the "environment" that the signals travel through changes. The interference patterns are very small in scale, where moving the phone by a few inches in any direction can create massive changes of 20 dB (a factor of 100) or more in received signal strength. A person moving, or leaves rustling on the trees outside create dynamic changes to the environment.
The implication is that whether a certain microwave allowed a call to ring or not could be simply dumb luck related to the dynamic environment of the RF signals travelling between the phone and tower.
The "Faraday cage" of the microwave oven is by no means perfect. Since the metal if the microwave box is not a perfect electrical conductor, there will always be some signal leakage, but it does act as a very good attenuator of the signal (60-70+ dB). Depending on the signal strength available outside of the oven (which has to do with many factors including distance to the tower, presence of trees foliage, ground topography, building materials used in the house, the RF fading environment discussed above, and more) the signal strength inside the oven will be 60+ dB less. Whether the phone rings or not in a given environment is the result of all these complex signal strength factors.
A better (but more complex/expensive) experiment would be to set up a signal source of a known strength inside of a microwave and then take measurements of the strength outside of the oven in a controlled environment such as an antenna range. You could also measure it versus frequency to see how it changes over common cellular frequencies.
*accidentally create a time machine
El psy kangaroo
Steins; Gate
El psy congroooooo
The first Faraday cage I built up (microwave) Did Not Leak RF radiation. I could not afford Samy Kamkars Faraday glove box 2-3000$ plus cost of Tap through inter face devices. You and Samy did a great job using test equipment, and multiple tests on different devices. The door is the weakest link on a fridge. If the door seal is ripped, or the latch is not tight the milk will spoil. Thanks for science and not opinion.
Samy Kamkar AND Physics Girl !!!
I'm having a ScienceGasm
I was just about to test this but my phone was dead.... so I searched YT and got you. SAMMY KAMKAR IS IN THE HOUSE! He's my hero!
Microwave ovens use "larger" forms of microwaves to cook food than the types of waves used by most cellphones. The Faraday Cage the surrounds the microwave's interior is designed to keep the microwaves inside the oven. But, if your phone uses the "smaller" waves by most phones they can pass into the microwave because the cage isn't usually designed to block them.
+Brian Straight Finally someone who is not an idiot.
***** and the video is wrong
+Dave Carsley no, the video is right. The vast majority of commercial microwaves use a frequency of 2,450 mhz.
+Brian Straight if by "larger" you mean 2,450 mhz, instead of 2,400. That falls within the frequency range of wifi signals, which they mentioned several times in this video.
+Brian Straight That's not quite how that works.. for electromagnetic waves in free space, the wavelength is equal to the speed of light in free space divided by the frequency. That means that em waves with higher frequencies actually have a smaller wavelength than those with lower frequencies. Meaning that actually the Wi-Fi signal and microwaves are "smaller." Also I'm not going to go through the proof, but whether or not a wave can propagate through an opening depends on the wavelength, and not the amplitude. So saying "smaller" or "larger" is ambiguous, even when used correctly.
I really like the way you're approaching the problem. Feels really well structured and eleborated.
This video was unsponsored by carcassonne :) The blur snub of an awesome game!
Nice, book of Art of Electronics over there.
At 5:33 the blur of the boxes goes out, lol
actually, you had some variables you didnt account for...
1 : Cell Towers.
The RF energy does not go from phone A - to Phone B directly, it goes through a tower first.
so, this can be the difference at peoples houses, who may have lived different distances from different towers.
and dont forget, there are 2 different links.
1 from the first cell to the tower
2 from the tower to the second cell
no information or energy is transmitted between the 2 cell phones directly.
2 : line of sight.
RF in this range is pretty much (but not totally) line of sight.
so, if the door of the microwave is pointed toward a large open window
it may have a better chance of working.
if its pointed away, and its a small window, or, in a room in the middle of the house
it may not work at all.
Signals can bounce off of hard surfaces, but get less each time.
think of going into a room with no lights.
if the door is open, you can still see, but, its not as bright
and this is coming from a tower blocks, or , miles away.
cheers,
Brad
senior RF design engineer.
Sprint PCS (retired)
So, anyways, if she is right, then Snowden did not know what he was talking about.
The door of the microwave has metal mesh in it.
None of you watched the full video or paid attention... She talks about variables not measured and interference not calculated... 😮 It is astonishing to me that all of the annoying comments correcting a woman in science come from men talking about things she actually spoke about in the video... However, I watch many other science videos with mens doing experiments or explaining things and comments are always of "how amazing the videos are", even when they clearly made a mistake and have to put a footnote on description (it's ok we are all humans), however, nobody even mentions... I wonder why 😅
6:56 the two blurred boxes unblurred
U should turn on the microwave
Ben bruh iz mi speeling 2 guud four u
That would be wasting phones.
+Ben
Yew
Huh. Didn't know that.
+Animatotron Instructions unclear; burnt house down
Try the dollar bill test. Put a dollar bill half way in and half out close the door see if you can pull it out. Move it around usually it is a place where the seal is not complete. As always fabulous explanations. Thank you.
Thank you physic girl!
(That's the closest I'll ever get to thanking a super heroine)
I'm glad you mentioned the position, orientation and distance away of the microwave from a cellphone tower, because it makes a huge difference. Cellphones can tolerate variations in received signal power of around 60dB which is a factor of one million. So an oven allowing a millionth of the signal in from a really close tower might be the same as no Faraday cage at all if the tower is at extreme range. Still it's mlldly worrying that any measurable amount of 2.4GHz energy escapes. Thanks, I enjoyed it. Bill Dixon
Oh, so you love microwaves too ♥
OH GOD THIS EXPLAINS A LOT OMG. I used to work somewhere with a walk in freezer and if i had my phone in my pocket it would lose signal when i went in the freezer but come back when I came out. It also blocks wifi signal so if you were trying to get wifi and standing on the opposite side of the freezer from the router you couldn't get signal. Amazing!
Samy is my hero
Very nice, and I think you got to one of the issues at the very end. the space between The grid matters. We are not dealing with inductive electric currents, we are dealing with electromagnetic radiation. The ratio of the grid openings and the frequency of the microwave radiation matters. Certain fractions of the frequency will block, and other fractions will allow passage. So you can have frequencies very close to the blocked frequency getting through.
Stein; gate, anyone?
Thanks for the fun, hands-on look at microwave radiation.
The Faraday cage ‘thumb rule’ is not hard and fast. It’s much more complicated. The screens are much more like filters with attenuation of wave propagation than a gate that stops frequencies of smaller wavelength. The classical picture is the wave equation with modes, and the quantum picture includes electron-photon interactions.
*No timetravel?*
A large part of why your phone will ring in some ovens vs others is due to your location. If you are near a cell site, you have a stronger signal so the attenuation of the oven cavity isolation isn't enough to prevent communications. This is likely why you got a Ring with the WiFi calling even though it is at the frequency that the oven cavity is supposed to block, the WiFi signal level was much higher where the oven was located.
I did some testing with my oven and I found that I get about -42db attenuation into the cavity with the door closed at WiFi channel 6. Remember that no shielding of anything is 100% and 40 db is a ton of isolation.
Yes ALL microwaves will leak!! In the case of my oven, if you assume 700 watts of RF in the cavity and -42db isolation that means that ~44mw are leaking. That is about 1/4 of the RF power from your cell phone that you hold to your head!! And with RF remember that the field strength is reduced with the square of the distance. Even if you hold your head against your microwave, you receive far less RF radiation then from your phone. Funny how us humans fear things irrationally yet hold no concern for something like our phone which exposes us to much more radiation...
You have a ton of friends with microwaves? I'm jealous.
+GelberFisch8 Do you not have friends or just all of your friends don't have microwaves?
+SergeofBIBEK take a wild guess :(
I have very few friends, but all of them have microwaves. I could never be friends with someone without a microwave.
hello, the grid is frequency selective. The hols work like radiating apertures. higher the frequency is greater is the leackage as you mentioned. I believe the shielding attenuation is around 35 to 40 dB at 2.4 GHz and this explains why you can still hear the microwaveoven even 20 m away on a special radio tuned to 2.4 GHz, or on a spectrum analyser.
a car is also a faraday cage, but you can call a cell phone in it :))
+HajoBenzin1 Yep, in some parts they talk about it as if Faraday cages blocked every kind of electromagnetic radiation by default, which is not true. Even in the actual Faraday cages meant for blocking radio signals you could see through them, i.e. doesn't block the visible spectrum.
+T Trindad no, they expressly defined that they were talking about the microwave range, between 1mhz and 6ghz, several times during the video.
+HajoBenzin1 A car is not a faraday cage. There are huge holes where any radio signal could get through: the windows, windshield, etc. Also the doors if, like alot of modern cars, the doors are made entirely of composite and not any metal at all.
A Faraday cage is not only about blocking radio signals, if a lightning strikes a car or a plane, you would be safe inside it, for example. Although a car would block radio if their wave length was roughly larger than that of the holes in it.
***** you'd be safe in a car because there is no conduction path, because the rubber tires are highly resistant. That doesn't make it a Faraday cage. That just makes makes it insulated.
Both cellular and wifi transmit on multiple frequencies... There are a wide number of standards (3G, LTE, etc) that your phone can try to connect to the local tower and then even within technologies like LTE there are multiple frequency bands. For instance AT&T 4G HSPA and HSPA+ use 850Mhz(Band 5) and 1900Mhz(Band 2) bands but it all depends on area if they own a license. LTE uses Band 17(700Mhz), Band 5(850Mhz), Band 2(1900Mhz), Band 4(1700/2100Mhz) currently. Similarly, your home wifi uses 2.4Ghz on the old standard but newer 5G devices transmit/receive on 5Ghz... so your friend's microwave could have been letting that through. The net is that the faraday cages used by microwaves have holes in them (so you can see the food) and those holes determine the frequencies that they block (wavelength needs to be smaller than those to get through). Enjoy your show and your enthusiasm.
The title of the video was very hard for me to read for some reason
did call and cell mess you up?
+Barrett Coleman Yap
+jesse ding
"Can you call a mobile phone in the microwave?"
Better?
hello.
1) cellular towers transmits in different frequencies, it can be 900 MHz, 1.8 GHz, 2.1 GHz, 2.3GHz and more depending on company, 2g 3g 4g and location and country, so in other words in 1 house your phone was connected on 3g at 1.8GHz for example, in another at 4g at 2.3GHz and maybe at 900MHz also....
2) The distance from your phone and the cellular tower greatly affects signal strength from some pico watts to some milli watts (huge difference)
3) your phone might actually lost its signal and then switch to another band so it can actually get a call like 2g signal, that means also the timing here makes a difference and your are coverage by your provider
4) make sure your microwave is properly grounded, this can also affect results
That Faraday cage explanation was bogus. A car is a Faraday cage too, yet you can still place calls while you're in a car. -__-
windows
TheRestOfTheWeek Your microwave doesn't have a window? What?
robertdevald Well yes there is a window, look close and you will see a metal mesh in the window.
To put it simple, if there wasn't any metal in the window the electromagnetic wave would go through with out any resistance. If there was a thick metal plate instead the resistance would be very high. The metal mesh forms a resistance to the electromagnetic wave, the resistance mainly depends on the size of the mesh and the wave length.
TheRestOfTheWeek Okay, good to know.
Perhaps the size of the holes in the mesh influenced the test in the video.
robertdevald I think the design of the door has a big influence, how well the door closes.
I know this won't get answered but I like it when you and veritasuim combined shows y'all 2 could put your minds together and be awsome
Oh, the holes in this video, bigger than the holes in a farday cage; what you have made into a video is unnecessarily worrying...
The distance between the tower and the microwave makes a difference, a big difference. The faraday cage would create loss in the signal path, if it is communicating with a nearby device or tower, there is more signal that can get in.
Quick science & maths time: if my microwave puts out 60dBm (1000W), to get that down to 5mW (7dBm) I only need to loose 53dB, which is well within the -120dB sensitivity of a regular cellphone. WiFi is another example, my router puts out 20dBm, take away 53dBm equals -33dBm, which should be plenty enough to get through the microwave door (at close range).
Bro this is a "physics" video aimed at the people who are: non believers in evolution, gravity, actual science. Pretty much Trump supporters.
+VideoInked and if unnecessarily alarmist
Physics Girl, you should look into wave guides and the size of the opening to let a freq through. Before I saw the video, I guessed that the phone would still operate in the microwave as you discoveted. The reason for my hypothesis was the theory behind wave guides and the size of the openings of the "mesh" on the microwave door.
Your video is awesome but the title isn't quite appealing.
What would you have titled it instead?
+Physics Girl "She puts her cell phone in the microwave. When I saw what happened next, I lost it!"
+Physics Girl "Can you send nude selfies to a cell phone in the microwave?"
+Physics Girl "Microwaves don't block cell phone signals because... Obama and stuff."
+Physics Girl I'm out of ideas. :(
I recently found out on my WiFi network (I use commercial equipment at home (I work in networking) so it can see things that you usually can't like rogue APs, what channels are they interfering, their signal power, etc) that my electric smart meter is producing five distinct WiFi signals that are very strong. And when I say strong, they are in the -50dBM range at over 50 feet from my own access point (AP) (the smart meter is outside my house completeley opposed to where my AP is), 3 walls, 1 celling and many metal conducts and home appliances in between. I never saw those signals before and all of a sudden they are there. I also see (at -80dBm though) the same kind signals from one of the nearby house smartmeter too.
So I pushed my investigation further because I didn't find it normal that my AP could catch signals that strong at that distance. I did the microwaves oven test like you did and what I found is getting me worried. I transformed by iPhone into a WiFi scanner (you can do that by using AirPort utilility and activating the Wi-Fi Scanner option) by using the Air Port utility and let it scan continuously. With that, you can now find the strenght of any wifi AP (up to 5Ghz) - and that is how I found out that it was my smartmeter that was emiting those signals.
I put my iPhone in the microwaves oven while the scanner was On and it could "see" all wifi networks in the area, including mine, the smartmeter, my neigbors, etc. But when I closed the door of the microwaves oven, it lost all wifi signals - and my own AP was barely 20 feet away but still lost its signal - except those 5 smartmeter signals that barely lost their strenght : from -50 dBm to -60 dBm.
Now I know I am writting this in 2022 and there was a lot of complains back in the 2010-era about the safety of these smartmeters, but working in networking and knowing a bit about signal strenght for network optimization - and also what they can do the more you are near an AP - I can testify that these are not healthy level of radiations that are emitted from that smartmeter that far away. The room in my house that is adjacent to the wall where the smartmeter is installed outside receives signal strenght of -30 to -40dBm - that's the same as being 10 feet from your own AP at home in straight line with no obstable in between. I don't have my mG reader with me, but I will and measure those signal to see how "cooked" we are getting each day.
1. Cell phone distance to tower? No consistancy from location to location.
Wifi was in the house where the cell tower may have been miles away or right near the house for different locations.
2. Cell phone antenna and receivers are more sensitive then ever. They can pick up insainly small signals.
3. Digital. Adds even more "sensitivity" to the phone system, allowing even weaker signals to be used.
4. The amount of leakage is small considering most ovens are 800 to 1000 watts.
5. Look into db attenuation and power. You will find an amazing fact about the effeciency of doubling your power, or how little of a difference 500 watts to 1000 watts make when compared to the difference between 0.5 watts and 1watt. "Weak" cell signals attenuated 30db are still very readable to a tower that is close.
6. 2.4 ghz and 2.45 ghz is 50 mhz apart..... take a look at how much and how different 50 mhz can make.
I really like what you do and the channel you have, however 1st rule of science...know and/or control the variables.
Lastly.... us crabby old guys have insane knowledge... feel free to ask sometime. May make reasearching easier.
Used to work for enterprise level wifi company, can confirm that if people are experiencing few minute wifi outages in the middle of the day, the first thing you check is how close they are to the break room and if there's a microwave in there
Cool video, but when I saw the title I was expecting more of trying to call it as your microwave your phone. Now that would be awesome.
+Matthew Purcell It just kills your phone. So, no awesomeness. :-)
great video!! shared many times on facebook!! well done!
One thing I would as a matter of warning with microwaves, skin is not easily damaged by microwave radiation because it has blood running through it or very close. The one body part that can be very sensitive is the cornea, because it has a very low circulation rate of fluid. Frequent blinking reduces the risk, but heating clouds the cornea and is accumulative so don't put your eyes up against the microwave while cooking unnecessarily, and blink frequently when doing so.
This video is so great. You started with a solid science concept and really followed it where it took you. Thanks for creating.
+YouCanScienceIt But, as she stated herself, she ignored too many variables to make it a good research. It makes nice watching, but the research was crap, haha. Fortunately she says it herself too.
Electronic engineering rocks, it's my profession. 23 years telecom. We used to just build leak detectors checking the door seals. Good job.
I thought it was the amplitude of the waves that determined whether or not they got through, not the wavelength. I learned something new today!
very good work on microwave, as I think the small holes grill help the phone for passing the microwave. These all depends on the type of the frequency.
Samy is the best (your garage door opener is in trouble!). Cute, Horowitz & Hill on the book shelf!
Our business is in a metal building. Some cell phone carriers' phones do not work well at all inside the building, while at least one works fine in most locations inside. My speculation is either the frequency, or the proximity to that carrier's tower.
Information is "lighter" than mass. A microwave's defenses are intended to prevent gross effects to outside masses, not to obliterate all information. As Mr Universe put it: "You can't stop the signal, Mal." In the 1980's, we put a Geiger-counter up to the view-screen of a microwave oven, and at a couple centimeters or so, it did register some extra clicks. Beyond that range, it was just background rate.
The microwave oven design assumes you won't smash your eyeballs right up against it for hours at a time, and it isn't intended to prevent pure information from being transferred. The distance-squared law works as its own buffer, so you don't get a "star-burn" from being out at night, but you can still see the constellations :)
I don't know how it is in the US but here in Austria we actually have multiple frequencies for 2G, 3G or LTE. The reason why it did or didn't work on a the microwaves could be that in a different region another frequency has been used from your phone.
We use 800 MHz, 900 MHz, 1800 MHz, 2100 MHz and 2600 MHz so if I were to test it here, chances are good that it will or will not work sometimes depending on the microwave and the cell tower frequency used ;)
That actually makes sense
I did not know that
Also, your phone might be on different network frequencies in different locations. Since phones operate on frequencies ranging from 800Mhz to 2500Mhz, your shielding may not have been ideal.
Very good video! i always knew this stuff. i climb cellular tower and install the cellular network and microwave dishes for towers. but finally somebody did a good video showing proof. which spectrum did you guys check? i saw 700. there is also 1900,850,2100 and 2600 usually for LTE. Thanks physics girl.
My HF 35C HF-Analyzer (800MHz-2700MHz) goes off the chart (above 2000 microwatts/square meter) when turned on "peak" signal with the range on 1999 microwatts/square meter, with my Cuisinart model CMW-100 microwave cooking. And no wonder, (though I knew it spewed out radiation, I didn't know why until tonight), I just found out that the door on my oven is loose even when it is closed! The leak is so bad that I had some time ago put up a faraday cage in my condo, with aluminum foil wrapped around both sides of large pieces of cardboard. This reduces the radiation hazard dramatically! But I still sit several meters (and even more feet) away from the oven when it is cooking. I think it's time I get another microwave.
This oven, which was supposedly a "refurbished" unit I bought used from an appliance sales and repair shop around last December. A true "refurb" would come in it's original box with the owner's manual. But this had neither. What it DID have was a loose screw in the back that required a special screwdriver I had to buy to tighten it. I believe I had actually paid somebody's past due repair bill. My previous unit was a new one from Sears that sold new (in 2013) for $54. After four years, it would cook EVEN WHEN THE DOOR WAS OPEN, despite the FDA standard to have two "failsafe" latches to make sure that never happens. Needless to say, I scrapped it right away. My point is this: the quality of microwaves has gone downhill since I bought my first one new in 1983, which was still working well in 2006, when I gave it away.
I was taught that Faraday cages only block RF from getting into the cage and you can transmit outward. Of course, there will be attenuation transmitting out, but none of the cancellation. Therefore microwaves would be designed to attenuate microwaves from escaping at the frequency generated by the microwave, i.e., microwaves are not Faraday cages. In addition, while most newer microwaves are at 2.4 GHz, there are microwave ovens at different frequencies. Cellular phones transceive at different frequencies and not at WiFi frequencies.
If I am wrong about the Faraday cage (and I may), please site references. The references I've seen, such as Wikipedia, Quora, etc. don't properly address the answer of transmissions escaping a Faraday cage (short of attenuation due to metal, not EMF cancellation).
You are very confused.
I have installed RF suppressed sound room, only to have my cell phone work fine inside. A RF engineer type explained the issue: modern cell phones are digital and tend to be pulssy in nature by the way the RF signal is transmitted/ modulated. This pulse just goes into the metal wall and a signal is inverted and come out the wall. AKA the whole room is a giant antenna.
I was not able to test this.
It's actually quite simple: the wavelength of 2.45 GHz in a vacuum is c/2.45GHz = 122 mm. As a rule of thumb, we say that once we get past a tenth of lambda, the transmission line behavior of materials is marginal. But that doesn't mean it's magically zero. When you're dealing with RF, it's all about loss. Your microwave can be just fine if it provides e.g. 60 dB of loss at 1 cm away, but that wouldn't mean you'd be able to pick it up with the hackRF one. I don't exactly know the specs of the hackRF one or a typical cell phone, neither of the amount of loss your microwave faraday cage induces, but if you would say have 900 Watts of RF-power in your microwave, that would translate to 59.54 dBm, subtract 60dB loss and you receiver only has to have a noise floor of about -.5 dBm. Now that's a little bit on the very sensitive side, so I'd say 60dB is grossly overestimating the loss your faraday cage induces, anyway, a faraday cage is not an RF-shield by no stretch of the imagination, think of it rather as insulation. If your signal is strong enough and your receiver is sensitive enough, you'll always be able to overcome the loss your cage induces.
Did you heard about "slot antenna"? It is just cut in metal sheet, whith some feed point near. So, microwave oven has door, which is practically the same slot if there are no additional metal contacts or some absorbing elements on the door.
Sometimes I take my tablet into the kitchen when I make food. I've noticed that if I run the microwave my wi-fi connection drops, but only nearby the microwave. I can still receive a signal in my room even though it has to travel through the kitchen to get to me.
I always found it interesting.
The doors of microwave ovens do not have a metal-to-metal connection across the gap, to seal in the microwaves. They have a wave trap around the door edge (under a plastic cover) that approximates the effect of metal-to-metal contact. But the effect is sharply tuned (doesn't work well at other frequencies) and is sensitive to (detuned by) dirt (greasy food coating) buildup. A clean microwave door contains microwaves, better.
A microwave oven is not a Faraday cage because the door seal is non-conductive. Microwaves would leak out through the door seal except that in the door frame there is a profiled strip of aluminium called a quarter wave choke, which absorbs radio waves of a specific wavelength and is designed to absorb the wavelength used by the oven. This means that if the phone in the oven is using the same wavelength it will be blocked (or at least it should be), but if it using a significantly different wavelength it will get through.
I've made a test where I put one mobile phone to tether it's wifi connection (with the mobile network on) and used another phone to connect to this wifi (with mobile network off). While "pinging" both phones to each other, I put the "access point" phone inside the oven and closed the door. The ping success output then stopped for a few seconds and returned shortly after. After that I took out the "AP" phone back from the oven, put the other phone inside and then I could notice the same behaviour. Using an Wifi Analyser app I could see that the wifi was working on 2.4 GHz frequency and the only thing that has changed was the signal strength. With the oven's door closed it went down significantly but with enough strength to maintain the connection between the phones.
Dear Physics Girl: I do not know if you in fact edit your own videos, but if you do, heres a tip. when trying to blur stuff out, make sure its actually fully blurred and not just half blurred. and and in your software when you add a transition like a fade, the blur goes away earlier than the video itself. (I am referring to the moment at 04:35 as an example of this.) other than that i enjoyed this video. have a nice day. cheers.
You have made your conclusion based on only one microwave.
My question have you tried the same setup for the rest of the microwaves you used in the beginning of the show?
I liked the video a lot where I watched it twice and that is the question that came to my mind
Thank you
This is good, a proper experiment that left me wondering about the results.
Cellular phones can make due with amazingly weak signals. Most modern phones have fractal antennas and can hold a call at -107dBm.
Microwave ovens are only made to shield against the radiation itself produce so not to cook the user but only the food inside it. This experiment say nothing about dangerous microwave leakage since a cellphone wich operate at a different (higher) frequency then the microwave ovens magnetron will not be affected by the mesh grill in the door. It all depends on the size of these holes in it related to the wavelength of the radiation. The shorter the wavelength (higher frequency) the smaller the holes have to be to appear as non transparent to the radiation. Visible light and microwaves are for example the same type of radiation ( electromagnetic ) only the wavelength is the difference. The much shorter wavelength of visible light allows it to get through the holes so we can se inside the oven while operating while remaining non transparent to the heat generating microwaves inside wich have a much larger wavelength so they safley remain inside. The cell phone also however have a shorter wavelength then the magnetron so it have no problem getting its signal through the door as well. I ve tried it myself and sure i could call it. Also a small leakage is not harmful, its when the power level reaches several watts and above wich can cause internal heating of the body it can be dangerous.
A good explanation except for one thing - cellular isn't shorter wavelength than wifi. It is longer. The key is that the oven is not (and is not intended to be) a perfect faraday cage. They all leak to one degree or another. And when you go cutting doors in them, they leak a lot.
One thing I didn't notice mentioned was that the most recent WiFi (802.11 n or 802.11 ac) actually runs on the 5 GHz bands which may go through the microwave shielding much easier.
* 802.11 n can actually run in 2.4 or 5 Ghz mode.
Thank you Physics Girl :)
My suggestion, if nobody else has done so: Measure the leaked 2.45GHz radiation off your microwave oven(s), using Samy's device, as a function of perpendicular distance r from the oven's door screen.
The amplitude of the leaked radiation should drop down as 1/r2, and does so very quickly, because of refraction - its wavelength is about 12cm, while the screen's holes' diameter is on the order of 3mm. Then the leakage is so little just, say, r=1cm outside of the oven's screen, that you can put your hand there while using the oven, and wouldn't feel a thing. It'd be cool to see the measurement data, though.
Actually, quick question, where were the cell towers for those places that you tested the microwaves at? The microwaves that block the cell RF might actually be far enough away that (if they are not perfect) the limited attenuation their providing, coupled with the inverse square law is causing the signal to fall through. OR if the cell tower was really close, it's RF output could have been enough to overcome the attenuation of the microwave enclosure. Same reason why the WiFi might have worked, Samy's WiFi AP might have been close enough to overcome the attenuation of the microwave.
...Yeeeaaah, having moved around a lot in the last few years we've used the wifi enabled cellphone in the microwave method to test whether a microwave is definitely not leaking. The thing is you don't know for sure whether the leak is harmless or if your microwave is defective, especially if you got it second-hand.
you may have missed one thing. A microwave oven puts out about 1000 watts of power where a cell phone puts out about 1mw of power. A microwave puts out 10, 000 times more power than a cell phone. If a low power cell phone can transmit such a low amount of power in the microwave this does not sound good to me at all, as a microwave is pumping much more power and more than likely that much more RF leakage.
Don't put your hands on or around the door of a microwave as you may receive an RF Burn....they burn from the inside out.
I have an RF burn to my hip where I had it pressed up against the railing on a ship that I worked as an electronics technician. I was wearing rubber gloves to protect my bare hands; but did not give it a thought when trying to steady myself on a rocking ship working on an antenna coupler.....this was a long time ago and now procedure has one limiting exposure that I did not have at the time I was in the Navy about 40 years ago. A RF burn, burns deep, often not felt right away, and may not leave a burn mark on the skin.
I was working in the vicinity of two 1000 watt transmitting antenna and a 35,000 watt radar system. A metal object that is not properly grounded can act as a re-radiator such as the railing on a ship. I question if the door on the leaking microwave has a good ground and I certainly would not put my hand on the door while it is in operation.