or losses in antenna tuners, etc.
Actually, for that matter, I think the FCC is a bit vague on where the
reference plane for the power limit is. Say I have a 5 kW amplifier, and
I'm using some sort of horrible lossy transmission line to connect to the
antenna. What's to keep me from saying that the output of the system should
measured at the antenna feedpoint (i.e. the transmission line is part of the
"transmitter".. it's not supposed to radiate). Particularly on higher
bands, this could be significant.
And, as a practical matter, when they come knocking on your door, it's going
to be as the result of field strength measurements (or a fink report from a
competitor, like in the Cable TV biz). It's not illegal, per se, to possess
the 100 kW RF amp (heck, you don't even have to have a license to own it),
just to radiate more than 1500WPEP, and if you have a credible story with
documentation and measurements to back it up.
Total Radiated power is a bit tricky.. where do you measure it? How would
you account for ground losses?
In any case, I think that the idea is to encourage folks to come up with new
solutions to the problem of communicating, rather than falling back on: Big
Amp, Big Tower. (even if this is the "towertalk" list, and towers are near
and dear to our hearts!)
----- Original Message -----
From: "Michael Tope" <W4EF@dellroy.com>
To: <va3pl@cuic.ca>; <towertalk@contesting.com>; "Jim Lux"
<jimlux@earthlink.net>
Sent: Wednesday, September 03, 2003 7:00 AM
Subject: Re: [TowerTalk] Smart antennas
> Actually, another possibility would be to normalize to 1500
> watts radiated power (vs. effective isotropic radiated power).
> This would allow the person with small lossy antennna
> elements (e.g. your HOA phased array) or somone with a
> really long feedline run to normalize for system ohmic losses.
> You would essentially prorate your RF output power by
> the difference between your antenna gain and its directivity
> plus any feedline losses. For an antenna that had -3dBi
> overall gain and 7dB of directivity, you could run 15 KW
> into the input connector. This would radiate the same power
> into space as a +7dBi gain antenna with 7dB of directivity
> excited with 1500 watts.
>
> 73 de Mike, W4EF................................
o/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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