1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice
Dismiss Notice
This forum does not allow a single user to have more than one username. If anyone wants to change their username contact an admin and it will be done. Multiple accounts belonging to the same member will be deleted without warning.

11 meter dipole help???

Discussion in 'Home Brew' started by Zeb98, Aug 27, 2011.

  1. Zeb98

    Zeb98 Member

    Joined:
    Aug 27, 2011
    Messages:
    5
    Likes Received:
    1
    Good point, my QTH is in a large neighborhood and I will have my neighbors help me watch for emissions should they occur; in such a case, I will invest in a balun. I plan to ground my station well also. I will have the revised antenna up this PM.

    I do have a problem fo power lines however they run across my back yard and along side what will be my shack. I my wish that I had built some sort of loop antenna before it ia all over with...anyhoe that will be yet another project;)


     

  2. Needle Bender

    Needle Bender ...he thinks it's funny that I stepped in it

    Joined:
    May 15, 2010
    Messages:
    1,403
    Likes Received:
    312
    my uncle made a camping antenna once when i was only 12. we were playing cb skip back then and he used a dipole and i remember he wrapped a coil (choke) what i thought he said was a "half-way" down for both polarizations. i didn't know what he meant back then but i do now. he wrapped a choke down 18' so he would have both a vertical and a horizontal 1/2 wave antenna and we talked skip all day and all night on that piece of rg59 from his truck with a tiny palomar tx50
     
  3. wavrider

    wavrider W9WDX Amateur Radio Club Member

    Joined:
    Jun 2, 2009
    Messages:
    3,366
    Likes Received:
    1,203
    This is mentioned in several low band DX articles, using the line isolator, rf choke, ferrite beads or whatever method of choice 1/4 wl down the coax to make the so called tripole or other words having both vertical and horizontal polarization.

    Wire antennas do work fantastic.
     
  4. wavrider

    wavrider W9WDX Amateur Radio Club Member

    Joined:
    Jun 2, 2009
    Messages:
    3,366
    Likes Received:
    1,203
    On 11 meters, running legal power you should not have any worries about CMC or RFI with the neighbors, hopefully.

    On the power line issue, run your antenna perpendicular to the electric wires, never run any wire antenna parallel with power lines as there is a very good chance of qsb being picked up from the electric wires.
     
  5. Zeb98

    Zeb98 Member

    Joined:
    Aug 27, 2011
    Messages:
    5
    Likes Received:
    1
    Update, OK I used a new so 239 connector, cut to length first then soldered connections, and I just used a piece of hard flat plastic and not over-complicated PVC tubing this time. I have 1.5 swr across the band at altitude; I think I will let it be. No balun no choke for now and I did away with the adjustable ends and simply cut to length. My new rig will be in Monday and I can really put it to use.

    I will buy a commercial antenna eventually and probably leave this one up. I got to thinking back and one time I also made a vertical dipole for 11 meters out of copper tubing and it seemed to have worked fine. I'm sure many more projects are to come.:thumbup1
     
    1 person likes this.
  6. Needle Bender

    Needle Bender ...he thinks it's funny that I stepped in it

    Joined:
    May 15, 2010
    Messages:
    1,403
    Likes Received:
    312
    if you pulled the middle back with a third line until it was close to 120 degrees in the horizontal vee it would probably drop to close to 1:1. i think a strait dipole is about 70 ohms
     
  7. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,832
    Likes Received:
    805
    I've never seen an SO-239 pulled apart from feed line weight. The metal housing/threads etc, are what furnished mechanical strength. The insulation and center pins are only there for the contacts, no stress applied to them. I don't think I'd worry about it much. If you really think some stress relief would help, add a feed line support. A 'chinese handcuff' type thingy on the feed line tied to the center insulator should take care of that. (There are knots that do the same thing, can't remember the names of them. Ask a Boy Scout?)
    Using the 'angle of the dangle', or the angle between the 'legs' of a dipole to reduce input impedance/SWR is a 'trick' as old as the hills. It works. If a 1.5:1 SWR bothers you, try changing that 'leg' angle. Nothing wrong with a 1.5:1 anyway.
    - 'Doc
     
  8. RickC.

    RickC. Hopeless antenna junkie

    Joined:
    Mar 30, 2009
    Messages:
    402
    Likes Received:
    7
    I didn't mean the SO-239 coming apart, I was talking about the integrity of the soldered joint to the center conductor (if I read the original post correctly). Depending on the mechanical strength of a soldered joint is a mistake. I believe that because of making that mistake a few times until I learned better!

    At any rate, 1.5:1 across the band is nothing to worry about, hang it up there and let it play.
     
  9. i remember thinking that , im sure others here did too . :D
     
  10. Beetle

    Beetle Sr. Member

    Joined:
    Dec 7, 2005
    Messages:
    3,017
    Likes Received:
    1,024
    I wouldn't worry about "picking up QSB". I'd be more concerned with picking up electrical noise. :whistle:
     
    1 person likes this.
  11. Zeb98

    Zeb98 Member

    Joined:
    Aug 27, 2011
    Messages:
    5
    Likes Received:
    1
    I have found an answer to my question about the swr changing at altitude. "A dipole antennas impedance increases as its distance from the ground increases." Thus, it decreases the antennas impedance as you lower it back down. I trimmed the antenna setting the swr close to the ground (7-8') for the desired frequency without taking into account the intended operation height (about 15'). In the future I will remember this.
     
  12. wavrider

    wavrider W9WDX Amateur Radio Club Member

    Joined:
    Jun 2, 2009
    Messages:
    3,366
    Likes Received:
    1,203
    :D Proximity to mother earth does make a difference, glad you got it working.
     
  13. "A dipole antennas impedance increases as its distance from the ground increases."

    can someone explain how that happens ?
     
  14. office888

    office888 Active Member

    Joined:
    Jun 8, 2009
    Messages:
    499
    Likes Received:
    15
    Make a dipole out of coaxial cable.

    No balun needed!
     
  15. Beetle

    Beetle Sr. Member

    Joined:
    Dec 7, 2005
    Messages:
    3,017
    Likes Received:
    1,024
    Coupling to earth (and things sitting on the earth, like buildings, trees, etc).

    A dipole in "free space", which is about as practical as a genuine isotropic antenna, has a feedpoint impedance right around 70 ohms. Closer to the earth, at easily attainable heights - say at 30 feet or so on 11 meters - it'll be lower; somewhere closer to 50 ohms.
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!