"Lancer" wrote in message
...
On Tue, 28 Oct 2003 23:10:42 GMT, "BuckEye" wrote:

I agree to all of the above except a 1/4 wave is a 1/4 no matter what. A
so
called loaded 1/4 is a loaded antenna not called a 1/4 anymore. Once a
antenna has been shortened by any means, shorter than the physical 1/4
wave
antenna ( 1/4 wave including the velocity factor ), top hats, loading
coil,
or ant other ways it is not clamed to be called a 1/4 wave anymore.
I did say 1/4 whip on the post, as most everybody should have known it
to
be the 108" antenna.


I don't know where Doc is heading for with his statement, but a
shortened antenna ( like the Xterminator) is 1/4 wave "electrically"

Velocity factor isn't a factor when you determine antenna length,
except certain antennas that are made from transmission line.

Maby you can explain how a antenna is 1/4 so called " electrically 1/4 " if
it is not a 1/4 wave like a 108" whip.
If it has a coil in it it, and shorter than the 1/4 it is a loaded antenna
NOT a electrically 1/4 wave equivelement .
If that was the case then a very loaded antenna that was 12" tall NOT 8'
could also be called a 1/4 wave "electrically"
What makes then a antenna 1/4 wave "electrically", because it matches the
50 coax?


Velocity factor IS importment when cutting a element to the proper
length.
Typically a antenna element can range from .91 to .99 of the true open space
length.

Here is a add from a supplier of the antenna.

SP-1000

HIGH PERFORMANCE TWIN 1/8" SQUARE COPPER WIRE COIL,
FREQUENCY COVERAGE 26-31MHz,
"SWR LESS THAN 1.5:1 1.5MHz SPREAD"
STANDARD 3/8" x 24 THREAD
OVERALL LENGTH 54" ( WHAT not a 1/4 wave only half the length )
Dam that makes it 1/8 wavelength in the physical length.
No where does it say 1/4 wave equivelement. The only thing that could be
called a 1/4 wave antenna is a is a 1/4 wave antenna.
Thats just another marketing tool to cause more confusion in the antenna
world.

Another add.

A3000, 59 inch long helically loaded 1/4 wave, wide band 26 to 29 Mhz.
Just another trick, What makes this antenna any different from other
antennas that are loaded to shorten them. Some of the others do not clam to
be a loaded 1/4 wave. Thats BS.
Thats about as dum as selling a equivelement shortened 12" ruller that
comes only 7' long.
Owell some believe it.

On Wed, 29 Oct 2003 02:52:33 GMT, "BuckEye" wrote:


"Lancer" wrote in message
.. .
On Tue, 28 Oct 2003 23:10:42 GMT, "BuckEye" wrote:

I agree to all of the above except a 1/4 wave is a 1/4 no matter what. A
so
called loaded 1/4 is a loaded antenna not called a 1/4 anymore. Once a
antenna has been shortened by any means, shorter than the physical 1/4
wave
antenna ( 1/4 wave including the velocity factor ), top hats, loading
coil,
or ant other ways it is not clamed to be called a 1/4 wave anymore.
I did say 1/4 whip on the post, as most everybody should have known it
to
be the 108" antenna.


I don't know where Doc is heading for with his statement, but a
shortened antenna ( like the Xterminator) is 1/4 wave "electrically"

Velocity factor isn't a factor when you determine antenna length,
except certain antennas that are made from transmission line.

Maby you can explain how a antenna is 1/4 so called " electrically 1/4 " if
it is not a 1/4 wave like a 108" whip.
If it has a coil in it it, and shorter than the 1/4 it is a loaded antenna
NOT a electrically 1/4 wave equivelement .
If that was the case then a very loaded antenna that was 12" tall NOT 8'
could also be called a 1/4 wave "electrically"
What makes then a antenna 1/4 wave "electrically", because it matches the
50 coax?

A coil in a short antenna cancels out the capacitive reactance making
the antenna resistive at the operating frequency. The coil makes it
"electrically" a 1/4 wavelength. More than likely it won't be 50
ohms, usually quite less, unless some kind of matching is used at the
base.



Velocity factor IS importment when cutting a element to the proper
length.
Typically a antenna element can range from .91 to .99 of the true open space
length.


The number (.91 to .99) are correct for the difference between an
antenna in free space and erected near earth. Its not from the
velocity factor of the antenna.
Its because the antenna is close to the earth and other
conductive objects (tree, buildings and power lines) which present
stray capacitance that tunes the antenna lower in frequency than a
free space antenna. Its called "end effect" and is more prevelant
the closer an antenna is other objects.

"Lancer" wrote in message
...
On Wed, 29 Oct 2003 02:52:33 GMT, "BuckEye" wrote:


"Lancer" wrote in message
.. .
On Tue, 28 Oct 2003 23:10:42 GMT, "BuckEye" wrote:

I agree to all of the above except a 1/4 wave is a 1/4 no matter what.
A
so
called loaded 1/4 is a loaded antenna not called a 1/4 anymore. Once a
antenna has been shortened by any means, shorter than the physical 1/4
wave
antenna ( 1/4 wave including the velocity factor ), top hats, loading
coil,
or ant other ways it is not clamed to be called a 1/4 wave anymore.
I did say 1/4 whip on the post, as most everybody should have known
it
to
be the 108" antenna.


I don't know where Doc is heading for with his statement, but a
shortened antenna ( like the Xterminator) is 1/4 wave "electrically"

Velocity factor isn't a factor when you determine antenna length,
except certain antennas that are made from transmission line.

Maby you can explain how a antenna is 1/4 so called " electrically 1/4 "
if
it is not a 1/4 wave like a 108" whip.
If it has a coil in it it, and shorter than the 1/4 it is a loaded
antenna
NOT a electrically 1/4 wave equivelement .
If that was the case then a very loaded antenna that was 12" tall NOT 8'
could also be called a 1/4 wave "electrically"
What makes then a antenna 1/4 wave "electrically", because it matches
the
50 coax?

A coil in a short antenna cancels out the capacitive reactance making
the antenna resistive at the operating frequency OK TRUE . The
coil makes it
"electrically" a 1/4 wavelength
Why does the coil make it that way.
Nowhere in any theory does it state that. Its just another ways to match the
coax to free air. That's all the antenna does.

Why do you keep trying to say its "electrically" a 1/4 wavelength. Just
because it
can be loaded with a matching device ? Shows a good match.
This could be taken to the extreme and if the antenna was reduced to only
one inch
in length, tuned and matched would it be electrically" a 1/4 wavelength .
No its just a resonate circuit with no relation to a
wavelength. In fact a conductor does not have to be any wavelength to
radiate at all.
When matched any length of wire will emit all the power applied to it.

More than likely it won't be 50
(We all know thats true)
ohms, usually quite less, unless some kind of matching is used at the
base.



Velocity factor IS importment when cutting a element to the proper
length.
Typically a antenna element can range from .91 to .99 of the true open
space
length.


The number (.91 to .99) are correct for the difference between an
antenna in free space and erected near earth. Its not from the
velocity factor of the antenna.
Its because the antenna is close to the earth and other
conductive objects (tree, buildings and power lines) which present
stray capacitance that tunes the antenna lower in frequency than a
free space antenna. Its called "end effect" and is more prevelant
the closer an antenna is other objects.

If so how do you explain in some long wire antennas its even 1.05 times
longer than the freespace.

BuckEye wrote:

Why does the coil make it that way.
Nowhere in any theory does it state that. Its just another ways to match the
coax to free air. That's all the antenna does.

Why do you keep trying to say its "electrically" a 1/4 wavelength. Just
because it
can be loaded with a matching device ? Shows a good match.
This could be taken to the extreme and if the antenna was reduced to only
one inch
in length, tuned and matched would it be electrically" a 1/4 wavelength .
No its just a resonate circuit with no relation to a
wavelength. In fact a conductor does not have to be any wavelength to
radiate at all.

Any antenna, even a straight piece of wire has inductance at radio
freqencies. A 1/4 wave straight piece of wire will exhibit a certain
inductance at a certain frequency, shorten it to something less than a
1/4 wave and the inductance decreases. Add a coil to make up the missing
inductance and the antenna "looks" like a 1/4 wave again to the RF
source. Some of the power is dissipated as heat in the coil because of
the I/R losses of the coil.

What makes a antenna so called " looks like a 1/4 wave again to the RF".

Where does it say a matching antenna must look like a 1/4 anyway.



"Add a coil to make up the missing
inductance and the antenna "looks" like a 1/4 wave again to the RF, not so,
the impedance is now very low at its feed point. Big mismatch (you forgot
the extra device now needed to match the antenna,usally a cap or coil on the
input side.so adding just a loading coil did not make it look like a
match.Notice I said a match . NOT a 1/4 wave. RF doesn't care what the
wavelength is. Where does it say a antenna must "look like a 1/4 anyway."
The same thing could be said about a base matched 5/8 wave antenna, it shows
a good match also and its is a long way from the 1/4 wave length. and is
never said it looks like a 1/4 to the RF.
Don't confuse a match to it looking like a 1/4.

There is many things that can be changed at the antenna mounting spot, 1/2
wave 5/8 wave

BuckEye,
But all antennas are 'matched', be they exactly a 1/4 wave
length long, or 75 feet long, or 1 inch long. I'm assuming
that you mean impedance matching, right? Impedance matching
has nothing to do with an antenna being resonant.
'Doc

What the hell do you think I am saying.
This all started when some dumass said a antenna was electrically 1/4 wave
long, not 1/4 wave antenna. You either have a 1/4 wave antenna or you
don't. If its shorter, then its not a 1/4 wave antenna. In most cases it
loaded, and no more electrically a 1/4 wave long antenna.
How hard is this to understand. I think this comes from some adds that's
states it a helical loaded
1/4 wave antenna that is only 56" long which is bull . Just like some other
adds that claim their antenna is a 5/8 antenna wound on a fiberglass rod
only 5' tall now go figure, I guess some also believe this .




"'Doc" wrote in message ...


BuckEye,
But all antennas are 'matched', be they exactly a 1/4 wave
length long, or 75 feet long, or 1 inch long. I'm assuming
that you mean impedance matching, right? Impedance matching
has nothing to do with an antenna being resonant.
'Doc

On Wed, 29 Oct 2003 04:42:45 GMT, "BuckEye" wrote:

Why does the coil make it that way.

Because it cancels out the capacitive reactance of the short antenna.

Nowhere in any theory does it state that. Its just another ways to match the
coax to free air. That's all the antenna does.

Sorry, yes it does.
Its not matching the coax,
its cancelling the reactance.


Why do you keep trying to say its "electrically" a 1/4 wavelength. Just
because it
can be loaded with a matching device ? Shows a good match.
This could be taken to the extreme and if the antenna was reduced to only
one inch
in length, tuned and matched would it be electrically" a 1/4 wavelength .

Yes.

A 1" antenna would have a capacitive reactance of 3,000 or greater.
When the reactance is canceled out, you would end up with an antenna
with a feed point impedance of 0.05 . It would be resonant, but
wouldn't match 50 ohm coax.

No its just a resonate circuit with no relation to a
wavelength. In fact a conductor does not have to be any wavelength to
radiate at all.

No, but to be resonant it does.

When matched any length of wire will emit all the power applied to it.


If you don't think that canceling out the capacitive reactance of a
shortened antenna doesn't change its electrical length, why does its
current distribution change?