"Duke Of Windsor" wrote in message
...
(Twistedhed) wrote in news:28004-40102BD9-249
@storefull-3256.bay.webtv.net:
From: ('Doc)
FWIW
A coil will always lower the power handling
ability of an antenna.
Balderdash. The coil will evenly distribute heat that would otherwise
fry a lesser, non-coiled antenna.
What he is trying to tell you is that a coil DOES reduce the efficiency of a
circuit as opposed to a straight wire.
That is something you can argue with all day long and it will still be a
fact. Any coil creates resistance. If you wind
a coil of say #18 wire, it will also CREATE more heat than that straight
wire. Where RF is concerned, in a given circuit, it will be resonant, but
that heat wastes RF
energy . Along with it, it will also be more "broad-banded" and tolerate a
wider range of frequencies. Now,
when you----and let's talk about antenna coils-- use a larger coil, YES! It
distributes heat better, but this is
again a result of less resistance. It is also called IMPEDANCE of which
there are 3 "resistances": feedpoint impedance, COIL resistance, and
radiation resistance. Now. We can't do much about radiation
resistance, but the other two can be used to advantage.
With the coil, again, it DOES dissapate heat AND its bandwidth becomes
NARROWER. That means that
if you are sitting still and the antenna's environment doesn't change (like
with those keydown events) the
antenna remains in resonance. If the vehicle is moved,
then it's effficiency *can* suffer because its environment
changes along with it. That cell tower that wasn't there
before now can have a BIG effect on the antenna's overall performance. It
also may not be as big an effect
at 27 MHZ as it would be at lower frequencies, but it
is an effect no less.
According to established antenna theory, a 102" whip
would outperform that big coil. The reason they don't
is that *most* users put the whip on the bumper and when they install a
Predator 10K, they put it on the tool
box (pickup) or the roof. Now the parameters have changed and the user now
believes that the coil is "better". Sure, it's better, but the coil antenna
now has
gained a height advantage.And this has as much to do with the antenna's
FEEDPOINT and proximity to the earth With the whip on the roof or tool box,
the coil should not outperform the 102: whip, but whips are impractical and
they don't *usually* end up on top because of their height.
Antenna theory is the same for any radio service whether it is CB or any
other.
Jerry
Yes Tipsy that is absolutely balderdash, you have no idea in your pea
brain
mind where maximum current flows is on a coil antenna.
Large coils lower it less than small coils, but
both large or small coils lower the antenna's
power rating. That's because of the resistance
of the coil. A fact of life, get used to it, it won't
change.
The resisitance of the "coil"?
I don't know what type antennas you have failed with in the past, but
you ought attend a keydown so you can se firsthand how your theory is
bunk in referring to those antennas specifically designed for power
capacitance.
The keydowns you speak of all the keyclowns used straight 1/4 wave
antennas
so who knows better you or them Tiposy
"efficient".
(snip)
No sense taking it further with you until you rectify your
contradictions. Both claims can not be true.
'Doc