I placed my cellphone inside my microwave. This notwithstanding, my step mother was able to call me, again. Is it a normal thing or I need to change of microwave ? I believed faraday cage of a microwave could stop these wavelength (900-1800 Mhz)...

By the way, It is an old microwave (bought fifteen years ago). Its frequency must be around 2.4 Ghz but I lost the manual, the door was well closed, I verified.

  • $\begingroup$ was the door left slightly open? $\endgroup$ – hyportnex Feb 20 '18 at 14:58
  • $\begingroup$ that right, yes it is around theses frenquency, I tought $\endgroup$ – snoob dogg Feb 20 '18 at 15:00
  • $\begingroup$ @hyportnex no! I closed it well $\endgroup$ – snoob dogg Feb 20 '18 at 15:02
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    $\begingroup$ @KyleKanos to avoid receiving calls from my step mother (as I said) -_- $\endgroup$ – snoob dogg Feb 20 '18 at 21:59
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    $\begingroup$ @KyleKanos sometimes you receive so much calls from your step mother that you act weirdly to avoid them $\endgroup$ – snoob dogg Feb 20 '18 at 22:01

The cage on your microwave works (probably). Does your hand get hot if you hold it nearby? If not, you have nothing to worry about. The cage only needs to cut down the power getting out by a factor of 1000 or so, and then it wouldn’t pose a threat to you.

With a cell phone, the radiation is in the same frequency range, but you’re dealing with a dramatically more sophisticated beast. Cell phones have variable amplifiers, error-correcting codes, and other engineering tricks that can handle a huge dynamic range of signal strengths, ranging from the enormous signal you’d get if you were standing under a cell tower all the way to the minuscule signal you’d get out in the wilderness. Remember, the power of the radiated signal from a tower decreases as $1/r^2$, so your phone has to be able to measure small signals to be useful. If you have a decent cell signal at your house to begin with, it doesn’t matter if you put the phone in a cage that drops the signal by a factor of 1000. That’s the difference between being away from a cell tower by 50 meters versus a mile: the phone can handle it.

  • $\begingroup$ How did you arrive at the factor of 1000 in power reduction to eliminate the hazard of leaking of a microwave oven? $\endgroup$ – freecharly Feb 20 '18 at 16:59
  • $\begingroup$ I just tried it myself. In my 12 year old microwave oven with 2.4 GHz frequency, my cell phone didn't react at all to a call when it was inside! $\endgroup$ – freecharly Feb 20 '18 at 17:09
  • $\begingroup$ @freecharly I’d say that a factor of 1000 is actually a conservative estimate. If you have a microwave that’s 2.5 kW/m^2 inside the oven, and the FDA regulation is no more than 5 mW/cm^2 leakage, then that works out to a factor of 50 attenuation if I’m not mistaken. But depending on the cage, it could be better or worse. Obviously the outcome of this experiment will be dependent on a number of variables, including design of the cage, design of your phone, and strength of the cell signal outside the cage. $\endgroup$ – Gilbert Feb 20 '18 at 17:20
  • $\begingroup$ The question remains how the allowed FDA microwave leakage standard relates to the penetration of the phone carrier wave into the microwave oven. How did you arrive at the 2.5kW/m^2 inside the oven? $\endgroup$ – freecharly Feb 20 '18 at 17:28
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    $\begingroup$ The FCC exposure limit to microwave radiation is 1 mw/cm^2, averaged over 30 minutes. (5 mw/cm^2 for six minutes.) rfcafe.com/references/electrical/… The surface area of a microwave oven is easily on the order 1000 cm^2 (about 1' x 1'). Microwave ovens operate at about 1 kW, so a factor of 1000 (30 dB) should be fine for safety. Cell phones have to operate over several orders of magnitude of signal strength, so it is altogether reasonable to expect that a person living near a tower can get reception inside a microwave oven. $\endgroup$ – Jim De Camp Feb 20 '18 at 18:47

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