Lots of hams use vertical coaxial-sleeve dipoles
with the coax feedline running up through the sleeve.
Lots of hams prefer end-fed antennas. Does anyone run
his coaxial-sleeve dipole horizontally?
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Lots of hams use vertical coaxial-sleeve dipoles
with the coax feedline running up through the sleeve.
Lots of hams prefer end-fed antennas. Does anyone run
his coaxial-sleeve dipole horizontally?
--
73, Cecil http://www.w5dxp.com

Those antennas have poor decoupling from the feedline,
unless you use decoupling devices of some type. I once
made one of those for 2m. In general, it was horrible when
using it with no decoupling. If I run a vertical half wave, I
actually prefer to base feed it, if I'm going to run it with no
additional decoupling sections. I would never end feed a
horizontal wire antenna unless it was a last resort. If I did,
I probably wouldn't even bother with trying to center feed
it like the coax sleeve antenna.
A vertical coax sleeve antenna needs cones, radials, chokes,
etc at the proper points on the feedline. Usually two sections
if you want good decoupling. The sleeves are probably the
most popular of the commercial versions.
If I ran an end fed half wave, I don't think there would be a
drastic difference between feeding from the end, or feeding
from the center with the coax sleeve version. Both have
their problems. If I run a dipole, I feed it normally from the
center, and the line runs away perpendicular to the wire.
IE: normal config.. The average 1/4 wave ground plane will
usually outdo a coax sleeve 1/2 wave, if the 1/2 has severe
common mode problems. This was the case on 2m for sure,
and it's most critical there. I never ended up using that coax
sleeve halfwave. My 1/4 GP smoked it on 2m.
MK

Cecil Moore wrote in
. net:

Lots of hams use vertical coaxial-sleeve dipoles
with the coax feedline running up through the sleeve.
Lots of hams prefer end-fed antennas. Does anyone run
his coaxial-sleeve dipole horizontally?


I use one on CW. Works good.

SC

wrote:
Cecil Moore wrote:
Lots of hams use vertical coaxial-sleeve dipoles
with the coax feedline running up through the sleeve.
Lots of hams prefer end-fed antennas. Does anyone run
his coaxial-sleeve dipole horizontally?
--
73, Cecil http://www.w5dxp.com

Those antennas have poor decoupling from the feedline,
unless you use decoupling devices of some type. I once
made one of those for 2m. In general, it was horrible when
using it with no decoupling. If I run a vertical half wave, I
actually prefer to base feed it, if I'm going to run it with no
additional decoupling sections. I would never end feed a
horizontal wire antenna unless it was a last resort. If I did,
I probably wouldn't even bother with trying to center feed
it like the coax sleeve antenna.
A vertical coax sleeve antenna needs cones, radials, chokes,
etc at the proper points on the feedline. Usually two sections
if you want good decoupling. The sleeves are probably the
most popular of the commercial versions.
If I ran an end fed half wave, I don't think there would be a
drastic difference between feeding from the end, or feeding
from the center with the coax sleeve version. Both have
their problems. If I run a dipole, I feed it normally from the
center, and the line runs away perpendicular to the wire.
IE: normal config.. The average 1/4 wave ground plane will
usually outdo a coax sleeve 1/2 wave, if the 1/2 has severe
common mode problems. This was the case on 2m for sure,
and it's most critical there. I never ended up using that coax
sleeve halfwave. My 1/4 GP smoked it on 2m.
MK

wrote:
Cecil Moore wrote:
Lots of hams use vertical coaxial-sleeve dipoles
with the coax feedline running up through the sleeve.
Lots of hams prefer end-fed antennas. Does anyone run
his coaxial-sleeve dipole horizontally?
--
73, Cecil http://www.w5dxp.com

Those antennas have poor decoupling from the feedline,
unless you use decoupling devices of some type. I once
made one of those for 2m. In general, it was horrible when
using it with no decoupling. If I run a vertical half wave, I
actually prefer to base feed it, if I'm going to run it with no
additional decoupling sections. I would never end feed a
horizontal wire antenna unless it was a last resort. If I did,
I probably wouldn't even bother with trying to center feed
it like the coax sleeve antenna.
A vertical coax sleeve antenna needs cones, radials, chokes,
etc at the proper points on the feedline. Usually two sections
if you want good decoupling. The sleeves are probably the
most popular of the commercial versions.
If I ran an end fed half wave, I don't think there would be a
drastic difference between feeding from the end, or feeding
from the center with the coax sleeve version. Both have
their problems. If I run a dipole, I feed it normally from the
center, and the line runs away perpendicular to the wire.
IE: normal config.. The average 1/4 wave ground plane will
usually outdo a coax sleeve 1/2 wave, if the 1/2 has severe
common mode problems. This was the case on 2m for sure,
and it's most critical there. I never ended up using that coax
sleeve halfwave. My 1/4 GP smoked it on 2m.
MK

I have good performance out of a sleeve antenna on vhf where the
sleeve was quite a bit larger tahn the coax running up the middle. RG
58 inside 1-1/4 inch sleeve. This was on a vertical antenna. Ferrite
beads aided in decoupling the coax, small bits of styrofoam were used
to keep the coax centered in the sleeve. Antenna was supporte by
placing it in a fiberglass tube. I could see how this could be a real
PITA to do horizontally.

"Cecil Moore" wrote in message
. net...
Lots of hams use vertical coaxial-sleeve dipoles
with the coax feedline running up through the sleeve.
Lots of hams prefer end-fed antennas. Does anyone run
his coaxial-sleeve dipole horizontally?
--
73, Cecil http://www.w5dxp.com


Hi Cecil

I dont propose that there is any practical reason to build a horizontal
coaxial-sleeve horizontal 1/2 wave dipole for HF. But your post suggests
to me an interesting way to build a fullwave "dipole". Two coaxial-sleeve
1/2 waves, end to end, might provide a method of low impedance feeding a
fullwave long horizontal "dipole". I might even try it at VHF.

Jerry

Jerry Martes wrote:
I dont propose that there is any practical reason to build a horizontal
coaxial-sleeve horizontal 1/2 wave dipole for HF.

The practical reason is when it is not practical to
center-feed a dipole. If one is forced to run the
coax feedline very close and parallel to one of the
dipole elements, might as well make the element hollow
and run the coax feedline inside it.

I wonder if that would work for a half-square? Make
one of the vertical sections hollow and run the coax
up the center of that section.

But your post suggests
to me an interesting way to build a fullwave "dipole". Two coaxial-sleeve
1/2 waves, end to end, might provide a method of low impedance feeding a
fullwave long horizontal "dipole". I might even try it at VHF.

There are two types of antennas called "sleeve" antennas.
One has the braid connected to the sleeve where the
1/4WL single center conductor emerges. The other has
the braid connected to the sleeve 1/4WL back down the
feedline from that point to achieve a shorted 1/4WL
stub sleeve.
--
73, Cecil http://www.w5dxp.com

JIMMIE wrote:


I have good performance out of a sleeve antenna on vhf where the
sleeve was quite a bit larger tahn the coax running up the middle. RG
58 inside 1-1/4 inch sleeve. This was on a vertical antenna.

They are good antennas if decoupled. Many have been used for
commercial/public service systems. A company called "Dodge" ??
used to sell a lot of them. Real heavy duty construction.. Their
version used two stacked sleeves. You could also use stacked
radial sets.
MK

Hi Cecil

If I have understood well your question, I think that the "Resonant
Feed dipole" (ARRL Handbook. 1996, page 20-17) is so much similar to
the clasical sleeve antenna. See in http://www.io.com/~n5fc/rfd.htm a
description.

Decoupling with his approach (choke) to the transmission line is poor
due high end Z.

I have modified it replacing coaxial choke transforming it in a coil
(less turns) made with the same coaxial but parallel tuned with a
condenser making these turns resonate (both terminals of condenser are
connected on the braid).

It is a good kite antennna (I am flying today with a Rokaku kite), and
a good solution for a good "windows in" dipole, without any tunner
neither earth connection...

Best Regards

Miguel Ghezzi (LU 6ETJ)

"Cecil Moore" wrote in message
. com...
Jerry Martes wrote:
I dont propose that there is any practical reason to build a horizontal
coaxial-sleeve horizontal 1/2 wave dipole for HF.

The practical reason is when it is not practical to
center-feed a dipole. If one is forced to run the
coax feedline very close and parallel to one of the
dipole elements, might as well make the element hollow
and run the coax feedline inside it.

I wonder if that would work for a half-square? Make
one of the vertical sections hollow and run the coax
up the center of that section.

But your post suggests to me an interesting way to build a fullwave
"dipole". Two coaxial-sleeve 1/2 waves, end to end, might provide a
method of low impedance feeding a fullwave long horizontal "dipole".
I might even try it at VHF.

There are two types of antennas called "sleeve" antennas.
One has the braid connected to the sleeve where the
1/4WL single center conductor emerges. The other has
the braid connected to the sleeve 1/4WL back down the
feedline from that point to achieve a shorted 1/4WL
stub sleeve.
--
73, Cecil http://www.w5dxp.com

I have never tried the latter method but I suspect you may have some of the
same problems as with first because the dielectric properties of coax outer
jacket really stinks at rf. What are the limits on the diameter of your
sleeve?