Is an antenna that is resonant on 10 meters still a 1/4 wavelength antenna
if it is physically only 4ft long or would this be an 1/8 wavelength
antenna(more or less).I am saying this should be called an 1/8 wl antenna
though I am arguing with those who generally know more more about this than
I. Not all the old timers disagree with me, so I am betting this is a pretty
common problem when discussing antennas.

"Jimmy" wrote in message
.com...
Is an antenna that is resonant on 10 meters still a 1/4 wavelength antenna
if it is physically only 4ft long or would this be an 1/8 wavelength
antenna(more or less).I am saying this should be called an 1/8 wl antenna
though I am arguing with those who generally know more more about this
than
I. Not all the old timers disagree with me, so I am betting this is a
pretty
common problem when discussing antennas.

You have to differentiate between electrical length and physical length.
Electrically, the antenna is a 1/4 wavelength antenna. Physically it is
0.125 wavelength tall.
Then again , you could do what the CB industry does and measure the length
of the wire and call it, say, a 1 wavelength antenna- meaningless.
Dale W4OP

In article , Jimmy wrote:
Is an antenna that is resonant on 10 meters still a 1/4 wavelength antenna
if it is physically only 4ft long or would this be an 1/8 wavelength

If the antenna is an electrical 1/4 wave then it is a 1/4 wave antenna, even
if it is physically shortened by use of coils.


Alex / AB2RC

Jimmy wrote:

Is an antenna that is resonant on 10 meters still a 1/4 wavelength antenna
if it is physically only 4ft long or would this be an 1/8 wavelength
antenna(more or less).I am saying this should be called an 1/8 wl antenna
though I am arguing with those who generally know more more about this than
I. Not all the old timers disagree with me, so I am betting this is a pretty
common problem when discussing antennas.

What you have is a *physically* short antenna that is *electrically*
1/4WL long. This usually involves a loading coil.

Also, the electrical length of a piece of coax is longer than it's
physical length because of the velocity factor less than 1.0.
--
73, Cecil http://www.qsl.net/w5dxp



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Jimmy,

I hope I am not providing flame fodder by saying you can call it several
things, but I believe this is certainly the case. I think "we" are all too
eager to engage in a symantics war rather than aiding to the understanding
of the OP.

What you see in this thread is that there are different ways of
describing the same thing and a netnews group is just about the best place
to find all those different ways. Based upon the way we each learned about
something, our method of discussing them is colored. There are frequently
several "mental models" which suffice for one physical thing.

*** Many of the posters understand, in their own way, what is going on, but
terminology can get complex and in the way sometimes. You will have to
develop the best "mental model" that works for you. Terminology will also
change over time in some areas.

Digression side bar:
The "J" antenna has come to be called the "J-Pole". "J-Pole" was a product
name for a commercial product with several "J" elements stacked on a
vertical "Pole" for gain. Odd. Nonetheless, I have become accostumed to
this and know what they mean. They also talk about "Wide band receive"
these days. "Wide band" used to refer to the bandwidth of the receiver's
IF as in wide band FM and narrow band FM. Now the term is used in place of
"General Coverage" receive.
End side bar:

If you are explicit in your description so the reader/listener knows what
you wish to talk about, you will be better off than trying to "latch on" to
one and only one "right" terminology. Then try your best not to get into
the symantic battles, but discuss the specifics.

Let's take your initial description:
Is an antenna that is resonant on 10 meters still a 1/4 wavelength antenna
if it is physically only 4ft long or would this be an 1/8 wavelength
antenna(more or less)
What to call it?

First, when you say "4ft long", preceeded by "...still a 1/4
wavelength..." we must decide just what the antenna is. Since you say
"still" 1/4 wavelength, you seem to be talking about a vertical which
"should be" a 1/4 wave, but we took out the clippers and it has been
shortened and is not physically 1/4, but half that length or 1/8 wave long.

Because you say "resonant", this tells us that something must have been
done to get it to resonate (take away the reactive part) since the 1/8 wave
is not resonant by itself. Therefore we can state that we do have an 1/8
wave radiator and a matching "thing" perhaps a loading coil. "Loading coil"
being the terminology we use to call a series (but not always) coil
somewhere on the antenna.
Because we have now made it resonate (by virtue of the addition of the
loading coil, or whatever) It is looking, from the transmitter or coax,
more like the full 1/4 wave physical length antenna -- because a REAL 1/4
wave hunk of iron-in-the-sky would also be resonant by itself.. From this
we can consider that it is now "Electrically" a 1/4 wave antenna, because
from the "electrical" point of view (that is from inside the coax and
"looking at the antenna" as a signal from the transmitter would) it appears
to be resonant (just like a 1/4 wave antenna).

Be careful with this "electrical" and "physical" talk. I have read threads
here where it gets very confusing with these two terms sprinkled
throughout -even when I'm familiar with the antenna under fire..

Now, doing the usual digression to a related, but not asked question...
The radiation pattern _WILL_ be that of the physical stuff in the air.
(this assumes that the loading / matching device is not a significant part
of the stuff doing the radiation -- not all that unreasonable of an
assumption). In this case, it radiates like an 1/8 wave antenna.
Unfortunately, an 1/8 wave isn't much different than the 1/4 wave ... thus
allowing more discuccion as to whether or not it is 1/4 or 1/8. ...more
digression... What I'm cautioning you about here is that it is the physical
antenna that determines the _radiation pattern_ and you can't get full-size
antenna performance with a smaller antenna and some magical circuit tricks
or matching tricks, or some yet undiscovered, super quantum theory based
wiggles on teh feed line of elements. You may get a pretty good antenna,
but it is the Iron-in-the-sky that makes a pattern...un-digress...

SO, what to call it?
My initial vote would be to start with "loaded 1/8 wave vertical". This
describes the physical antenna (a not optimim one) , then what was done to
make it work better. I think calling it a 1/4 wave antenna is misleading
for most people. You, not I, can take a vote what is brought to mind if you
just say it is a "1/4 wave vertical". I'll bet most will think _1/4 wave
physical_.

You can go further and describe the loading system furtherlike:
Center loaded, 1/8 wave vertical.antenna.
Base loaded, 1/8 wave vertical.antenna.
Top loaded, 1/8 wave vertical.antenna.
Shortened, 1/4 wave vert doesn't do too badly...

Then there's the "counterpoise" to consider. If you strung radials at the
bottom "1/8 wave ...ground plane" is in order. If not, then "ground
mounted 1/8 wave ..." may be called for.

In other words...describe it well and there should be less misunderstanding
as to just what your subject is.

OK flamers, knock yourself out...
--
Steve N, K,9;d, c. i My email has no u's..










"Jimmy" wrote in message
.com...
Is an antenna that is resonant on 10 meters still a 1/4 wavelength antenna
if it is physically only 4ft long or would this be an 1/8 wavelength
antenna(more or less).I am saying this should be called an 1/8 wl antenna
though I am arguing with those who generally know more more about this
than
I. Not all the old timers disagree with me, so I am betting this is a
pretty
common problem when discussing antennas.

On Tue, 20 Jan 2004 20:19:39 GMT, "Jimmy"
wrote:

Is an antenna that is resonant on 10 meters still a 1/4 wavelength antenna
if it is physically only 4ft long or would this be an 1/8 wavelength
antenna(more or less).I am saying this should be called an 1/8 wl antenna
though I am arguing with those who generally know more more about this than
I. Not all the old timers disagree with me, so I am betting this is a pretty
common problem when discussing antennas.

A 1/2 wave dipole on 10 meters is about 16 feet. So 4 feet sounds like
1/8 wavelength, physically, to me.

Unless it has a loading coil -- which could make it, electrically,
"longer" than 1/8 wavelength.

Bob
k5qwg

Steve,
All things considered, I don't see how your post can be
flamed. In fact, it's one of the better discriptions I've
ever seen (meaning I'm gonna steal it!).
'Doc

Jimmy, I don't see the connection between "resonant" and "1/4-wavelength",
at least from what you posted. And, in this universe, 4 ft. is NOT 1/4 on
10 meters...

- KI6PR
El Rancho R.F., CA

"Jimmy" wrote
Is an antenna that is resonant on 10 meters still a 1/4 wavelength antenna
if it is physically only 4ft long or would this be an 1/8 wavelength
antenna(more or less).I am saying this should be called an 1/8 wl antenna
though I am arguing with those who generally know more more about this
than
I. Not all the old timers disagree with me, so I am betting this is a
pretty
common problem when discussing antennas.

If the antenna is an electrical 1/4 wave then it is a 1/4 wave antenna, even
if it is physically shortened by use of coils. Alex / AB2RC


If that is true, then there is no such thing as a 5/8 wave antenna. They
would be 3/4 wave antennas.

Don't think so. 73 Al Lowe N0IMW

In article , Arrow146 wrote:
If the antenna is an electrical 1/4 wave then it is a 1/4 wave antenna, even
if it is physically shortened by use of coils. Alex / AB2RC


If that is true, then there is no such thing as a 5/8 wave antenna. They
would be 3/4 wave antennas.

since when does 5/8 = 3/4 ?
last time I checked, 3/4 = 6/8




Don't think so. 73 Al Lowe N0IMW