On 7/23/2012 4:03 PM, Jeff Liebermann wrote:
On Mon, 23 Jul 2012 12:41:32 -0500, John S
wrote:

From the document you posted, P*G/(4*Pi*D^2) = E^2/(120*Pi)
Let G = 1, D = 3, E = 200uV then
P*1/(4*3.14*3*3) = (200e-6)^2/377 and
P/113 = 40e-9/377 so that
P = 113 * 106e-12 giving
P = 12e-9
This looks like NANOwatts to me.

Well, that looks right. I'll do the short version:

From Pg 29.
http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf

Assuming a 0dBi gain antenna:
Power = 0.3 FS^2
where
FS = field strength in Volts/meter
P = Watts
Plugging in:
Power = 0.3 * (200 uV/m)^2 = 0.3 * (200*10^-6 V/m)^2
Power = 0.3 * 4*10^-8 = 12*10-9 = 12 nano watts.
Argh... You're right.

Thanks for that concession.

However, that can't be the correct maximum power. It's much too low
to be useful.

Well, maybe.

Digging out a cheat sheet from:
http://www.ti.com/lit/an/swra090/swra090.pdf
CEPT (European) 1e and 1e1 are 10mw and 1mw respectively.
However, digging down to the FCC stuff on Pg 11, I find that the specs
are really in FCC 15.231(b).
http://louise.hallikainen.org/FCC/FccRules/2012/15/231/
and are approx 11,000 uV/meter. Grinding the numbers again...


Yes, but you are reading only part of the regulations. These are
PERIODIC radiators. Please read the whole thing and tell me how often
and for what period you can transmit.


Thanks for catching my mistake and I'll double check the numbers
(again) when I get home from some service calls.

Very well. Please point out the pertinent parts that allow this
(undisclosed) mode of operation.