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Old August 20th 08, 11:33 PM posted to rec.radio.amateur.antenna
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Richard Clark wrote:
On Wed, 20 Aug 2008 10:23:11 -0700, Jim Lux
wrote:

The very last study, on the very last page with the second paragraph
offers:
"For an effectively transmitted power of 0.25 W,
the maximum averaged SAR values in both cubic
and arbitrary-shaped volumes are, respectively, about
1.72 and 2.55 W kg-1 for 1g and
0.98 and 1.73 W kg-1 for 10 g of tissue."
The last study gives us more exposure data (the discussion of which
inevitably scatters in the rhetorical wind of debate). I can only
wonder if the reader can draw a conclusion from this quoted sentence
that can be expressed in temperature rise. There's enough data to do
this, only intelligence remains to perform.


that's pretty simple.. Assume that the tissue has the specific heat of
water. 1 Joule will raise the temperature of 1 gram of water about 1/4
degree C..


That's a rise of 0.015 degree/second, or 10 degrees in 10 minutes. In
reality, you won't see that much rise, because bloodflow carries some of
the heat away, and so does convection.



Thanx Jim.

Exactly. If this proves anything, it proves that those who are not
worried about stepping out into the sun, but fear exposure to their
cell phone, they will always be worried about their cell phones.

Actually, it's not quite *that* simple..

The simple analysis is just for thermal effects. One has to also ask
whether there are significant "athermal" effects. These can come from
several potential sources. First, one can consider whether the
radiation itself can do anything.. well, the photon energy at microwave
frequencies is so low that it's orders of magnitude below any known
chemical reaction's activation energy.

Or, one can consider E or H field effects. If the E field is high
enough, it can depolarize a neural membrane, for instance, and cause
false neural impulses. That would be an acute effect.

One also needs to consider peak vs average effects. One could probably
power a defibrillator from a cellphone battery quite nicely, and that
can dump a few hundred joules at just the right time to cause some
serious problems. Again, though, that's an acute, not exposure/chronic
effect.
 
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