|
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 |
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 |
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 |
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 |
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 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.690 / Virus Database: 451 - Release Date: 5/22/2004 |
"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 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.699 / Virus Database: 456 - Release Date: 04/06/2004 |
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 |
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 |
"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. |
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 |
| All times are GMT +1. The time now is 02:02 PM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
RadioBanter.com