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..

So, dump 2.55W/kg and you get about 0.0006 degree rise per second.
Hang on the phone for, say, 10 minutes (600 seconds) and you'll get a
temperature rise of a bit less than 1/2 degree C.

For comparison:
putting your head in sunlight results in an incident flux of about
1kW/square meter (peak). Assuming skin reflectivity of 0.36, the flux
being absorbed is about 640W/square meter. Let's assume that the energy
is absorbed in the first centimeter of your skin/bone, and that your
head is a circle about 10cm in radius (e.g. 314 square centimeters)..
That works out to about 20 watts total power being absorbed (compare to
the 0.25W RF in the example above). Again, let's say that the density
is 1g/cc, so the 20W is being dumped into 0.314 kg, or a SAR of 64 W/kg.

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.

Let's approach this from first principles. The battery in the phone
is the only source of power. My own as an example has by the
manufacturers rating -
From Nokia for their 6263 model:
BL-5C 1020 mAh Capacity;
Talk time GSM up to 3 hours 20 min;
Stand-by GSM up to 11.25 days
Dump that capacity at a potential of 3.6V for the full talk time after
a fresh charge gives us 1.10 W PER HOUR.

Put 3 1/2W 51 Ohm resistors into a series circuit across the terminals
of a 12V DC Source, hold the resistor pack (less than 1cM²) against
the skin (I used my earlobe) and you have a literal tissue test under
the full power capacity of the battery as used continuously in a Nokia
6263 EXCEPT 100% of that power is lost to heat entirely - nothing
towards the display, nothing towards the RF, nothing towards the
speaker, nothing towards the microprocessor, etc. ALL of the heat is
confined with nothing towards the greater mass of tissues in the CNS.

What is the temperature rise? As measured using a fever thermometer
on the opposite side of the lobe: from 98.0°F to 99.4°F for 11.82V
@0.0778A after several minutes. Cut the blood flow by tightly griping
the lobe/pack/thermometer, and you can push this up another 6°F. As
Jim offers in his last comment, blood flow makes all the difference
(unless the creationists are worried about the tumor inducing effects
on corpses).

You have to first ask yourself, how to make the RF "grip" the tissue
to lower blood flow to raise temperature.

Next you have to ask how to make the RF ignore the mass of tissue. An
ear lobe is highly insulated from the heat absorbing bulk of the
skull. Ask any creationist why God chose large ears for animals that
have to shed heat that can't escape their fur covered bodies.

Next you have to ask how to make the Total conversion of battery power
into RF (lossless, perfect source) available for total, selective
absorption in the tissue.

All questions above are for the worriers to dwell upon and to conspire
to fulfill through creationist scienz (ironically "blame God" would be
their answer). First, 1020mAh is maximum available battery capacity.
Other ratings for a replacement battery range as low as around
500-750mAh. You may elevate the earlobe temperature by 1.4°F - but
not for long.

This particular Nokia model operates as high as 2.1GHz (14cM band) and
would require an extremely complex antenna (pointed directly into your
skull) to focus a beam in a 0.6cM³ cube (1/16th wavelength area within
less than a wavelength from the antenna). As the medicos would say:
the application of a directional antenna of these design requirements
for a general coverage service is contra-indicated.

Unless someone comes up with other figures (you will need the
creationist un-approved full four function calculator), it would seem
that nothing less than navel gazing can propel this thread further.

73's
Richard Clark, KB7QHC