Re: Heat comment (Q: Which ear do you use for your mobile phone?)

["Richard L. Hess" <lists@richardhess.com>]

OK, may I now get cranky? I think we need to really look at what's going on 

with these temperature measurements and show a bit of reality.



At 02:38 AM 09/09/2002 +0000, Bjorn Cedervall wrote:



>1. Temperature without a mobile phone: 34 degrees C.

>2. Temperature with a mobile phone held against the ear but not turned on: 

>37 degrees C.



OK so that brings it up to body temperature. That means there is no heat 

loss from the ear to the environment. The ear normally is a good heat sink 

with all the blood flowing through it and sitting out there flapping in the 

breeze.



>3. Temperature increase with NMT phones: 1-2 degrees C (we don't have NMT 

>phones in Sweden any longer).

>4. Temperature increase with GSM phones: About 0.5 degrees C.



With the phones pressed against the ear and operating???



GEEZE. We don't know where that heat is coming from. Sure it could be 

coming from the heating effect of the output off the antenna, but there are 

inefficient electronic devices in the phone. The phones get HOT. Lots of 

electronic equipment gets hot. Get over it. If you put a soldering iron 

against your ear it would burn you. It wouldn't be from the radio waves. It 

would be from the mains power flowing thru the heating element.



I design broadcast facilities. Our signals leaving the facilities are in 

the neighborhood of 10milliwatts each (satellite uplinks are often 

remote--I'm talking the landline copper or glass). The facilities consume 

perhaps a megawatt or more. We have to have special air conditioning. It 

has to be redundant.



Your laptop computer gets hot. Put the bottom of a 600MHz Dell against your 

ear. (I measured mine at various points between 42 and 48C.)



Can we please do MEANINGFUL tests???



Place a cell phone with a remote antenna so that the antenna is in the 

normal place. Measure the increase in the ear temperature (perhaps with a 

dummy cellphone pressed against the ear).



Do not confuse thermal heating with RF (microwave) radiation heating. One 

is like the soldering iron, the other might be bad for you, but let's 

isolate the one that might be bad. Oh yes, the thermal heating might be bad 

for you to in the case of the soldering iron, but you won't hold it there 

very long!



Sorry for being so cranky, but this one irked me. Ruth W. and I discussed 

it offline last week. I'm starting to feel some of the frustration that you 

folks feel. I've worried about cooling electronic equipment for 30+ years.



Oh, and Bjorn, just in case your perfect English misinterprets my 

frustration, it is NOT at you...it's with the non-scientific, "scientific" 

studies. I'm not usually this cranky in public, but this list seems to 

engender it and I'm starting to see why in an area I know and 

understand.  If you want to talk about the design of cooling systems for 

electronics, I'm probably not the worlds greatest expert (by a long shot), 

but I understand the issues and can get by.



Cheers,



Richard



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