Microwaves and Radio

[[Tycho?]]

As a small experiment, I put my mobile phone in the microwave (microwave is off) and called that phone with my cell phone. The mobile phone worked fine, despite being inside the microwave with the door closed.

 

I am confused about this. I was under the impression that the mettal grid that blocks the microwaves is simply a faraday cage, and hence should block all EM radiation at or below a certain frequency.

 

The mobile phone opperates on 2.4Ghz. Microwaves use 2.45Ghz for cooking, according to wikipedia. My question is how the phone signal was able to get through the microwave.

[5614]

the faraday cage would have been designed to block higher frequency EM waves and therefore the radio waves could penetrate it.

 

if it were a solid metal box no EM waves could get through but because this is using holes it can (i think that's it anyway!).

[[Tycho?]]

I thought if a faraday cage could block frequency x, it would be able to block all frequencies lower than x.

[5614]

that's what i thought although i couldnt see another explanation.

 

however, it is possible that the radiowaves could penetrate the other sides of the microwave-(cooking) unit.

 

furthermore those figures will obviously vary with differing mobiles and microwaves-(cookers).

 

it is possible that the faraday cage on the microwave-(cooker) is not 100% EM-wave-proof.

 

also mobile phones do have a bit of microwaves emiited from them in addition to the traditional wireless radio waves... these could all be explanations to your problem.

[swansont]

How do you know the phone worked? If all you did was notice that the ringer worked, I don't know if that's a good test. Triggering the ringer may require very little power, for example. Did you actually try to transmit information?

[5614]

well he may have spoken to the microwave through the phones, however i highly doubt that there was anyone in the microwave listening to the quality of the transmission!

[Rasori]

He could put an audio recorder in there and turn the phone's volume up. Or, if it's a picture phone, just send a picture

[5614]

a sound recorder would not record quality sound off a quiet mobile phone any way so it would not be a fair test.

[Guest Greeniemax]

Ok... probebly the Microwave oven has one source on one side and a absorvent metal on other side, when microwave pass through food and hit the absorvent materal (which would result in production of heat or electricity, I assume it's electricity, which is passed on as ground.

 

This other 4 sides of the microwave don't have to block the microwave as microwave travel in striaght line (till reflected or refracted).

[Ophiolite]

Repeat the experiment in a second micro-wave.

[YT2095]

He could put an audio recorder in there and turn the phone's volume up. Or, if it's a picture phone, just send a picture

and 5614.

 

Swansont mentioned sending Info, Audio qual is going to be a HUGE problem isn`t it! WHO is going to hit the Answer key on the phone? LOL

 

when he said Info, a Text Msg would suffice, and as rasori said too, a picture would be just as good

[[Tycho?]]

Well I finally repeated the experiment, got interesting results.

 

The phone did not ring. So I took it downstairs to a microwave which we dont use anymore, and tried it in there. It didn't ring there either, until I opened the door, when it immediatly started ringing. It makes sense for them not to ring of course.

 

I really do not know why it rang the first few times I attempted it. The only possibility I can think of is that the door wasn't properly closed, even though I know it was.