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Old June 3rd 04, 09:07 PM
hello
 
Posts: n/a
Default A horizontal "sleeve" antenna for 20m


HI
I want to put a dipole for 20m in my garden.
A tree and the home roof will be ok to fix the extremity.
My problem is the feed point : If IA center feed it , the feed line will
just hang at the center of the garden, something not acceptable by the
YL :-)

So I'm looking for a way to feed it by one "side".
I could endfeed it, but impedance matching is not so easy at such a high
impedance.
Then, after reading lots of post in this newsgroup, I read about the
sleeve antenna : generaly a vertical dipole where one leg is a sleeve.
Coax enter in the sleeve to the center feed point.
I think this antenna could work horizontaly and for HF and solve my
problem. Now, hanging horizontaly a 5m long metallic sleeve is surely
not a good idea, but at HF , I thing that man could replace the sleeve
by some wire cage.
So I end up with the idea of a cage or biconic dipole , with the coax
entering horizontaly in the middle of the cage to the center.

What do you think of this idea ?
How many wire for the cage 2 (a bowtie), 3, more ?
Do you have a better one for my particular constrains ?

Lots of questions, but I'm sure you will have lots of answers !

Thanks in advance

Thierry
F4DWV
  #2   Report Post  
Old June 3rd 04, 09:41 PM
Irv Finkleman
 
Posts: n/a
Default

hello wrote:

HI
I want to put a dipole for 20m in my garden.
A tree and the home roof will be ok to fix the extremity.
My problem is the feed point : If IA center feed it , the feed line will
just hang at the center of the garden, something not acceptable by the
YL :-)

So I'm looking for a way to feed it by one "side".
I could endfeed it, but impedance matching is not so easy at such a high
impedance.
Then, after reading lots of post in this newsgroup, I read about the
sleeve antenna : generaly a vertical dipole where one leg is a sleeve.
Coax enter in the sleeve to the center feed point.
I think this antenna could work horizontaly and for HF and solve my
problem. Now, hanging horizontaly a 5m long metallic sleeve is surely
not a good idea, but at HF , I thing that man could replace the sleeve
by some wire cage.
So I end up with the idea of a cage or biconic dipole , with the coax
entering horizontaly in the middle of the cage to the center.

What do you think of this idea ?
How many wire for the cage 2 (a bowtie), 3, more ?
Do you have a better one for my particular constrains ?

Lots of questions, but I'm sure you will have lots of answers !

Thanks in advance

Thierry
F4DWV


Use two pieces of copper tubing for the elements. Connect one to the
center of the coax, the other to the braid. Bring the coax out through
the lower piece. This is also known as a coaxial-sleeve and a few other
variations on the name.
--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/
Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/
Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada
  #3   Report Post  
Old June 4th 04, 08:43 AM
Hans Sundkvist
 
Posts: n/a
Default

Hi Thierry.

A simple way to do this is to use a coax as ts the sleeve.

Just cut the coax to a 1/4-wave, connect a 1/4 wire to the inner=20
conductor at one end of this coax, and feed the other end of the coax=20
through a choke balun, and there you have it: A simple inexpensive=20
coax-sleeve antenna.


73 de Hans, SM3PXG
=D6stersund
Sweden



hello wrote:
=20
HI
I want to put a dipole for 20m in my garden.
A tree and the home roof will be ok to fix the extremity.
My problem is the feed point : If IA center feed it , the feed line wil=

l=20
just hang at the center of the garden, something not acceptable by the =


YL :-)
=20
So I'm looking for a way to feed it by one "side".
I could endfeed it, but impedance matching is not so easy at such a hig=

h=20
impedance.
Then, after reading lots of post in this newsgroup, I read about the=20
sleeve antenna : generaly a vertical dipole where one leg is a sleeve.
Coax enter in the sleeve to the center feed point.
I think this antenna could work horizontaly and for HF and solve my=20
problem. Now, hanging horizontaly a 5m long metallic sleeve is surely=20
not a good idea, but at HF , I thing that man could replace the sleeve
by some wire cage.
So I end up with the idea of a cage or biconic dipole , with the coax=20
entering horizontaly in the middle of the cage to the center.
=20
What do you think of this idea ?
How many wire for the cage 2 (a bowtie), 3, more ?
Do you have a better one for my particular constrains ?
=20
Lots of questions, but I'm sure you will have lots of answers !
=20
Thanks in advance
=20
Thierry
F4DWV


  #4   Report Post  
Old June 4th 04, 09:14 PM
hello
 
Posts: n/a
Default

Irv Finkleman wrote:
hello wrote:

HI
I want to put a dipole for 20m in my garden.


So I end up with the idea of a cage or biconic dipole , with the coax
entering horizontaly in the middle of the cage to the center.



Use two pieces of copper tubing for the elements. Connect one to the
center of the coax, the other to the braid. Bring the coax out through
the lower piece. This is also known as a coaxial-sleeve and a few other
variations on the name.


OK, but for 20m , it means 2x5m of tubing. Not so easy to hang over the
garden.

DO you think that a wire cage qith 3 ou 4 wire could have the same
effect than tubing ?

Thierry
F4DWv
  #5   Report Post  
Old June 5th 04, 02:23 AM
Hal Rosser
 
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Default

How about a 20-meter J-Pole (hear me out) - it is an end-fed half-wave ----
just mount it horizontally
it feeds from one end - so there you go.

Hal
w4pmj

"hello" wrote in message
...

HI
I want to put a dipole for 20m in my garden.
A tree and the home roof will be ok to fix the extremity.
My problem is the feed point : If IA center feed it , the feed line will
just hang at the center of the garden, something not acceptable by the
YL :-)

So I'm looking for a way to feed it by one "side".
I could endfeed it, but impedance matching is not so easy at such a high
impedance.
Then, after reading lots of post in this newsgroup, I read about the
sleeve antenna : generaly a vertical dipole where one leg is a sleeve.
Coax enter in the sleeve to the center feed point.
I think this antenna could work horizontaly and for HF and solve my
problem. Now, hanging horizontaly a 5m long metallic sleeve is surely
not a good idea, but at HF , I thing that man could replace the sleeve
by some wire cage.
So I end up with the idea of a cage or biconic dipole , with the coax
entering horizontaly in the middle of the cage to the center.

What do you think of this idea ?
How many wire for the cage 2 (a bowtie), 3, more ?
Do you have a better one for my particular constrains ?

Lots of questions, but I'm sure you will have lots of answers !

Thanks in advance

Thierry
F4DWV



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  #6   Report Post  
Old June 5th 04, 08:50 PM
Smog
 
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"hello" wrote in message
...

HI
I want to put a dipole for 20m in my garden.
A tree and the home roof will be ok to fix the extremity.
My problem is the feed point : If IA center feed it , the feed line will
just hang at the center of the garden, something not acceptable by the
YL :-)

So I'm looking for a way to feed it by one "side".
I could endfeed it, but impedance matching is not so easy at such a high
impedance.
Then, after reading lots of post in this newsgroup, I read about the
sleeve antenna : generaly a vertical dipole where one leg is a sleeve.
Coax enter in the sleeve to the center feed point.
I think this antenna could work horizontaly and for HF and solve my
problem. Now, hanging horizontaly a 5m long metallic sleeve is surely
not a good idea, but at HF , I thing that man could replace the sleeve
by some wire cage.
So I end up with the idea of a cage or biconic dipole , with the coax
entering horizontaly in the middle of the cage to the center.

What do you think of this idea ?
How many wire for the cage 2 (a bowtie), 3, more ?
Do you have a better one for my particular constrains ?

Lots of questions, but I'm sure you will have lots of answers !

Thanks in advance

Thierry
F4DWV


Will this be any good ?
http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=5703371491
--

Jim Burrill (Smogthemog)
M1BMW
Kiteaholic
www.jbphonetech.info



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  #7   Report Post  
Old June 6th 04, 05:52 AM
Tom Bruhns
 
Posts: n/a
Default

Hi Thierry,

Yes, the cage idea should work well. I'd recommend 3 wires as the
very minimum, and I think 4 or more would be better. It also helps if
the form a cone, like the "Isopole" antennas, so the cage is well away
from the coaxial feedline, which would be centered in the cone.

If you use coax with a "copperweld" (copper-clad steel) center
conductor, perhaps you can strip 5 meters of the jacket and braid off
the end of the coax, and the coax is then one continuous run. In
fact, you can probably just cut the jacket and braid off of a short
section 5 meters from the end, to make the job easier. Then attach
some wires, even thin ones, to the feedline braid and run them back
along the line.

I'd recommend a choke balun, perhaps a few cm further along the line
from where the cage wires end. For single band use, you can coil up
some coax and even bridge across the coil with a capacitor to tune it,
connecting the capacitor to the braid -- that trick is useful if you
want to keep the coil small.

Cheers,
Tom


hello wrote in message .. .
HI
I want to put a dipole for 20m in my garden.
A tree and the home roof will be ok to fix the extremity.
My problem is the feed point : If IA center feed it , the feed line will
just hang at the center of the garden, something not acceptable by the
YL :-)

So I'm looking for a way to feed it by one "side".
I could endfeed it, but impedance matching is not so easy at such a high
impedance.
Then, after reading lots of post in this newsgroup, I read about the
sleeve antenna : generaly a vertical dipole where one leg is a sleeve.
Coax enter in the sleeve to the center feed point.
I think this antenna could work horizontaly and for HF and solve my
problem. Now, hanging horizontaly a 5m long metallic sleeve is surely
not a good idea, but at HF , I thing that man could replace the sleeve
by some wire cage.
So I end up with the idea of a cage or biconic dipole , with the coax
entering horizontaly in the middle of the cage to the center.

What do you think of this idea ?
How many wire for the cage 2 (a bowtie), 3, more ?
Do you have a better one for my particular constrains ?

Lots of questions, but I'm sure you will have lots of answers !

Thanks in advance

Thierry
F4DWV

  #8   Report Post  
Old June 10th 04, 06:50 PM
hello
 
Posts: n/a
Default


Many thanks for all the answers.
After all, I will try the horizontal Jpole.
It was my first idea but, I read lots of bad thinks about this antenna
(in particular in this newsgroup), but it's so easy to build that I
could try.


Thierry
F4DWV
  #9   Report Post  
Old June 10th 04, 10:46 PM
Steve Nosko
 
Posts: n/a
Default


"hello" wrote in message
...

Many thanks for all the answers.
After all, I will try the horizontal Jpole.
It was my first idea but, I read lots of bad thinks about this antenna
(in particular in this newsgroup), but it's so easy to build that I
could try.


Thierry
F4DWV


//nit alarm on//
It's not a J-POLE. It's a J antenna. The J-POLE was a commercial antenna
possibly by Cushcraft some time ago. It was a pole with several Js stacked
vertically on it for gain. The J antenna goes back as far as my handbooks
do at least the 40's.
I'd call this an end fed half wave. What's the matching device? A
quarter wave shorted stub.
//nit podium off//

Registered member of NPA - Nit Pickers Anonomous

How come I don't see any of you guys at the meetings?
Also, how come the phrase "how come" means "why", sort of?

--
Steve N, K,9;d, c. i My email has no u's.


  #10   Report Post  
Old June 17th 04, 03:55 AM
Al - VA3KAI
 
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Default

Thierry,

Check out the following URL - great feedback on eHam.net Reviews from users.
Might solve your problems for many bands!

http://www.parelectronics.com/end_fedz.htm

Al, va3kai

"hello" wrote in message
...

HI
I want to put a dipole for 20m in my garden.
A tree and the home roof will be ok to fix the extremity.
My problem is the feed point : If IA center feed it , the feed line will
just hang at the center of the garden, something not acceptable by the
YL :-)

So I'm looking for a way to feed it by one "side".
I could endfeed it, but impedance matching is not so easy at such a high
impedance.
Then, after reading lots of post in this newsgroup, I read about the
sleeve antenna : generaly a vertical dipole where one leg is a sleeve.
Coax enter in the sleeve to the center feed point.
I think this antenna could work horizontaly and for HF and solve my
problem. Now, hanging horizontaly a 5m long metallic sleeve is surely
not a good idea, but at HF , I thing that man could replace the sleeve
by some wire cage.
So I end up with the idea of a cage or biconic dipole , with the coax
entering horizontaly in the middle of the cage to the center.

What do you think of this idea ?
How many wire for the cage 2 (a bowtie), 3, more ?
Do you have a better one for my particular constrains ?

Lots of questions, but I'm sure you will have lots of answers !

Thanks in advance

Thierry
F4DWV



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