Antenna Pattern: Carolina Windom
 

I am installing a Carolina Windom Short 80 and am not sure which way to
orient it.

The company which sells the antenna says that because the antenna has a
vertical section which radiates; the antenna is omni-directional.

But others say that it radiates best in the direction of the ends.

Some disagree saying that a dipole is a dipole and so its antenna
pattern would be optimally broadside to the antenna.

Since the antenna is not center-fed; if it were a dipole the lobes along
the longer section would produce more signal; is that the case here.

Is this a good antenna or just so much bs?

Thanks.

--
3D 4 ME

Antenna Pattern: Carolina Windom
 

lid wrote:
I am installing a Carolina Windom Short 80 and am not sure which way to
orient it.

... the antenna is omni-directional.
... radiates best in the direction of the ends.
... a dipole is a dipole ...

See for yourself.

http://www.radioworks.com/ccwpat.html

An OCF has a distinctly different radiation pattern from
a dipole on certain frequencies. The vertical radiating
section of the Carolina Windom modifies the horizontal
radiation pattern.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Antenna Pattern: Carolina Windom
 

On Thu, 15 Oct 2009 16:38:52 -0400, lid
wrote:

The company which sells the antenna says that because the antenna has a
vertical section which radiates; the antenna is omni-directional.

That should be the end of it, then.

But others say that it radiates best in the direction of the ends.

Amusing but false.

Some disagree saying that a dipole is a dipole and so its antenna
pattern would be optimally broadside to the antenna.

Possibly so, if the company who sells the antenna is wrong. Or
possibly so, if the user who bought the antenna from the company
doesn't follow installation instructions which lead to a vertical
section that radiates.

Since the antenna is not center-fed; if it were a dipole the lobes along
the longer section would produce more signal; is that the case here.

Amusing but false.

Is this a good antenna or just so much bs?

Many users are satisfied. If they were to replace it tomorrow with a
design that was roughly the same over-all length, with the same
over-all match, then it they would report no differences could be
observed.

The only consideration that may fail in this proposed substitution
would be in the vertical section that radiates. The significance of
that polarization could be high, especially if the orientation of the
horizontal sections are not particularly well suited to your intended
propagation path.

In some points of the compass, your windom may exhibit interesting
polarization diversity that comes as a happy surprise; at other points
of the compass, you may need this diversity, and it isn't there
bringing a brooding disappointment. Such oddities spread over the
population of users make blood enemies and faithful converts.

73's
Richard Clark, KB7QHC

Antenna Pattern: Carolina Windom
 

In article ,
wrote:

I am installing a Carolina Windom Short 80 and am not sure which way to
orient it.

The company which sells the antenna says that because the antenna has a
vertical section which radiates; the antenna is omni-directional.

But others say that it radiates best in the direction of the ends.

Some disagree saying that a dipole is a dipole and so its antenna
pattern would be optimally broadside to the antenna.

Since the antenna is not center-fed; if it were a dipole the lobes along
the longer section would produce more signal; is that the case here.

If it *were* a half-wavelength dipole, I don't believe that the
direction or strength of the lobes would depend on the point at which
it were fed... center, off-center, or end (as in a Zepp).

This antenna doesn't look like a simple dipole to me. It appears to
be a combination of a doublet/dipole with the ends folded back, and a
vertical section which is deliberately designed to radiate.

The radiation pattern is going to vary, between the horizontally-
polarized component (from the flat-top and folded-back sections) and
the vertically-polarized component (from the vertical radiator between
the matching unit and the line isolator).

Horizontally-polarized radiation from the flat-top section is (I
think) going to be primarily off to the sides (perpendicular to the
wire) when the antenna is used on 80 meters, and probably on 20 meters
as well (due to the presence of the resonator stubs). On other bands
it'll be a more complex pattern, with multiple lobes. I'd expect a
null directly off of each end, on all bands.

Vertically-polarized radiation will be near-omnidirectional, and will
tend to fill in the horizontally-polarized nulls off of the end (and
the inter-lobe nulls in other directions on other bands).

The angles of maximum radiation for horizontal and vertical components
of the signal will almost certainly be different.

In short, it's going to have a complex radiation pattern which will
vary both horizontally and vertically, and will differ from one band
to the next.

Is this a good antenna or just so much bs?

Haven't used it myself, and so I can't say for sure.

Based on its design and what I expect its radiation pattern to be, I'd
guess that it's a decent overall performer, with fewer "dead spots"
than a dedicated half-wavelength dipole, slightly lower gain in some
directions, possibly better DX performance than a low-mounted dipole
(due to vertically-polarized radiation from the vertical section) but
possibly more prone to pick up close-in manmade noise (also due to the
presence of the vertical section).

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Antenna Pattern: Carolina Windom
 

wrote in message
...
I am installing a Carolina Windom Short 80 and am not sure which way to
orient it.

The company which sells the antenna says that because the antenna has a
vertical section which radiates; the antenna is omni-directional.

But others say that it radiates best in the direction of the ends.

Some disagree saying that a dipole is a dipole and so its antenna
pattern would be optimally broadside to the antenna.

Since the antenna is not center-fed; if it were a dipole the lobes along
the longer section would produce more signal; is that the case here.

Is this a good antenna or just so much bs?

I am not sure what the short 80 is. I have a home built one that is up
about 50 feet and installed as flat across the top as two end supports and a
middle support will let it be. It is about 80 feet on one side and 40 feet
on the other side. The coax drops 20 feet down from the 4:1 balun to the
current choke.

It seems to work fine for me on 80 meters, the only band I normally work
with it. I have an 80 meter dipole up about 40 feet on one end and 20 feet
on the other end at right angles to it. In just about all cases the OCF is
beter than the 80 meter dipole. Only problem is when I run an amplifier the
4:1 balun overheats and the swr goes way high when I run more than about 700
watts ssb. The balun is rated for 1.5 KW.
When I had it fed with rg8X and a low power balun without the lower current
choke I could not tell much differance. I was only running 100 watts then
as I did not have an amplifier. There did seem to be some rf in the shack as
the computer speakers would make noise, but not with the current choke in
the line with the new antenna. Both antennas were ran to a 5 way antenna
switch just inside the window I was passing the coax through. The shack is
in a walkout basement and the switch has a wire ran outside to a ground rod
and that rod is also connected to another rod about 10 feet away and also to
the house ground rod about 10 feet in another direction.
With the choke and larger rg8 coax there does not seem to be any rf in the
computer speakers.

It seems to work well in all directions. I don't know if it is because of
the vertical section or just because it is only 50 feet up.
The lower 80 meter dipole seems not to be very directional either.

Antenna Pattern: Carolina Windom
 

There's no single answer because, as Cecil said, the response changes
markedly with frequency.

Maximum radiation will be broadside at frequencies where it is a half-
wave, and it will progressively develop multiple lobes and nulls as
the frequency is increased.

The common-mode current on the "vertical radiator" tends to fill in
some of those nulls, but its contribution is also very frequency-
dependent.

Here's an example of the difference that the "vertical radiator" makes
to a 132ft OCF dipole on 20m - one of the bands where it has most
effect. Red trace is the azimuth response at 10 degrees elevation
without the vertical radiator; the blue trace is with it:

http://www.karinya.net/g3txq/temp/ocf_low_angle.png

73,
Steve G3TXQ

Antenna Pattern: Carolina Windom
 

Hi Steve,

Thanks for the azimuth plot. This was just what I was looking for.

I am on a sand dune above Lake Michigan 32 miles east southeast of the
Sears Tower.

The antenna that I am writing about is the Radio Works 80 Special with
41¹ and 25¹ element lengths. The radiating coax is 10¹ strapped to a
fiberglass mast. The dipole feedpoint is 30¹ above the sand and about
90¹ above Lake Michigan across the road. It is broadside to due north.

I get a lot of contacts from Georgia, Texas and the US northwest but
nothing from Europe, Japan or Australia.

I work 20m ssb primarily and so have cut and put up a 3/2 wavelength
centerfed dipole; slightly different location but same orientation with
an aluminum mast. Similar performance on 20. With the Palstar tuner; it
loads on 40.

My choices come down to keeping the Carolina Windom up, taking it down
or re-orienting (But I am squeezed by 7200v powerlines and large oak
trees in a terminal forest.).

It would be useful to have azimuth plots for 40 and 80 for this antenna;
if for nothing else than a starting point.

Thoughts?

Rick
W9ZD

Antenna Pattern: Carolina Windom
 

On Oct 16, 9:28*am, wrote:
Hi Steve,

Thanks for the azimuth plot. This was just what I was looking for.

I am on a sand dune above Lake Michigan 32 miles east southeast of the
Sears Tower.

The antenna *that I am writing about is the Radio Works 80 Special with
41¹ and 25¹ element lengths. The radiating coax is 10¹ strapped to a
fiberglass mast. The dipole feedpoint is 30¹ above the sand and about
90¹ above Lake Michigan across the road. It is broadside to due north.

I get a lot of contacts from Georgia, Texas and the US northwest but
nothing from Europe, Japan or Australia.

I work 20m ssb primarily and so have cut and put up a 3/2 wavelength
centerfed dipole; slightly different location but same orientation with
an aluminum mast. Similar performance on 20. With the Palstar tuner; it
loads on 40.

My choices come down to keeping the Carolina Windom up, taking it down
or re-orienting (But I am squeezed by 7200v powerlines and large oak
trees in a terminal forest.).

It would be useful to have azimuth plots for 40 and 80 for this antenna;
if for nothing else than a starting point.

Thoughts?

Rick
W9ZD

I got to try a Windom antenna over a really good ground system and was
pretty much amazed at the performance. The antenna was a
decommissioned LOM antenna waiting for the bulldozers for about 2
years. Good grounds certainly make a difference.

Jimmie

Antenna Pattern: Carolina Windom
 

Antenna Pattern: Carolina Windom
 

Michael Coslo wrote:
wrote:

Thoughts?

Maybe time to download EZnec?

The OCF antenna can work very well. I put one up once because the place
where the coax dropped was really handy to my shack entrance. It worked
"well". I did some QRP into California on 80 meters during a contest,
and I worked what I heard. That doesn't specifically mean that the
antenna performed well, but it does mean that I worked QRP into
California on 80 from the middle of PA.



How will you model the radiating feedline? I suppose one could just put
a "wire" in the model to represent the coax shield (which is what
radiates) and tie it to something useful. Someone's probably figured
out what the equivalent impedances are for the "isolator" and "balun"
that form part of that antenna. Maybe googling "NEC model Carolina
Windom" might turn up something useful.