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.

Antenna Project

Discussion in 'Home Brew' started by JDemoret, Apr 27, 2009.

  1. JDemoret

    JDemoret Member

    Joined:
    Mar 5, 2009
    Messages:
    41
    Likes Received:
    0
    Well after a couple of weeks experimenting with an end fed wire antenna for 11 meters and trying to get the matching cicuit right (and fighting with my OCD :blink:) I have started the "final" design of my vertical ground plane antenna. Once I got the matching circuit right (photo 1), I ended going with an air wound coil and a coax capacitor which brought the SWR down to 1.5:1 on the wire antenna and I'm pretty confident I can get this setup to work with the vertical. I was able to pickup some aluminum tubing that is 7/8" in diameter and about 5' long. I joined them with a two foot wooden dowel and a coupler made from conduit and hose clamps (photos 2 & 3). The overall length is 22.5 feet and seems to be very strong and lightweight. Photo 4 is the completed radiator attached to the base and the enclosure for the matching cicuit. Photo 4 also shows the mount and support which is pressure treated 2x4's I had laying around which is designed to transfer the wind stress around the base and enclosure straight to the antenna mast which will be 1.25" conduit extending all the way to the ground from the roof peak. Photo 4 shows the antenna attached to my pool deck and is currently going through wind testing. So far so good, had a good windy one on Saturday and the only thing I had to change was the length of the radiator support, the weight of the antenna was pulling it over from upright.
    More to come. Any suggestions welcome.



    John
     

    Attached Files:


  2. JDemoret

    JDemoret Member

    Joined:
    Mar 5, 2009
    Messages:
    41
    Likes Received:
    0
    More pictures.
     

    Attached Files:

  3. JDemoret

    JDemoret Member

    Joined:
    Mar 5, 2009
    Messages:
    41
    Likes Received:
    0
    and more pictures.

    Photo 1 is the original support (sagging bad)

    Photo 2 is the extended support (much better)

    Photo 3 is the ground radials. They are 6' aluminum tomato stakes which i ran 102" of 14ga copper wire down the length and it extends about 2' off the ends.
     

    Attached Files:

  4. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,781
    Likes Received:
    2,167
    Very cool. It seems you've worked out the mechanics of it all. Looking forward to your results.
    My 5/8 vertical has worked out well after trial and error. It is going to be up for a long time I think.
    Tell us more.
     
  5. JDemoret

    JDemoret Member

    Joined:
    Mar 5, 2009
    Messages:
    41
    Likes Received:
    0
    Will keep you updated. I've been working on making it as beefy and lightweight as possible. Have not made any "electrical" connections yet, I am going to leave it up as is for a few days as we are supposed to get some wind and storms and want to see how it does.(y)

    John
     
  6. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,832
    Likes Received:
    805
    After what happened to the last one, a wind tunnel test doesn't seem completely unreasonable, huh? :)
    And I also think you will find that since it's so close (touching) that wooden support, the tuning/matching is going to be slightly different, and will change when things get wet. Probably not a large change but still a change, which is normal.
    - 'Doc
     
  7. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,781
    Likes Received:
    2,167
    What I had to do was to lengthen and double (one piece of PVC inside the other) the pipe coming out of the top of the 4"x1/2;4" adapter and use that for additional support.

    See Five-Eights Wave Redo
     
  8. JDemoret

    JDemoret Member

    Joined:
    Mar 5, 2009
    Messages:
    41
    Likes Received:
    0
    Doc, I haven't had a failure yet but I did see what Homer's did and wanted to avoid that if at all possible. All the wood is going to painted with exterior paint, should I insulate the antenna from the support or will that make any difference? The support goes up the antenna about 3' so very little of the radiator if physically blocked by the support.

    John
     
  9. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,832
    Likes Received:
    805
    Oops! So I got the two of you confused. I'm real good at that sometimes! (Oh $#;+, now which one do I apologize to??)

    I think painting that wood would be a good idea. Not because it'll change what happens with the antenna, but to keep it from the normal weathering process. How it will affect that antenna is because of it being 'close' so it won't change that part. Unless that paint is conductive, and don't bother asking, I have no idea. :)
    - 'Doc

    ................
    MEMO
    From: Subconscious
    To : 'Doc
    Would you please pay attention! Look how you are embarrassing me. It ain't easy being you, you know. Don't make it any harder!
     
  10. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,832
    Likes Received:
    805
    Just for grins, the attachment is from that 23rd edition with a little modification (added the colors). 'Blue' is for distance between antennas, 'red-ish' if for the phasing lines. It's NOT enough information to do the phasing correctly, just an example of 'wazinda' book.
    - 'Doc
     

    Attached Files:

  11. Moleculo

    Moleculo Administrator
    Staff Member

    Joined:
    Apr 14, 2002
    Messages:
    8,898
    Likes Received:
    1,056
    Nice project! To the front page with you!!!
     
  12. JDemoret

    JDemoret Member

    Joined:
    Mar 5, 2009
    Messages:
    41
    Likes Received:
    0
    Thanks for the advise and comments. I'm going to leave it where it is for a couple of days to see how it does in some weather and to get caught up on the honey do list :headbang. Working on getting the ground radials ready to attach. Will post the pogress as it goes along.

    John
     
  13. JDemoret

    JDemoret Member

    Joined:
    Mar 5, 2009
    Messages:
    41
    Likes Received:
    0
    Got back to working on the antenna today and got the ground radials attached and the matching circuit hooked up and results were good (y).

    Channel 1 1.4:1
    Channel 20 1.3:1
    Channel 40 1.2:1

    Putting in about 22 watts.

    Did not have to use the coax capacitor, actually results with it on were really poor. Tap point on the coil was typical, about 2 turns down. First contact was about 50 miles north of me with the feed point of the antenna about 6ft. off the ground (y).

    Next job is to get it on the house and about 35ft. up.

    More to come.

    John
     
  14. JDemoret

    JDemoret Member

    Joined:
    Mar 5, 2009
    Messages:
    41
    Likes Received:
    0
    Well, for the last week or so I've been putting the antenna through it's paces and doing some tweaking and getting all weather-proofed getting ready to get it up on the house in it's final position. Here are the final results:

    Radiator length: 23ft.
    4 ground radials at 102" each.

    SWR readings:
    Channel #1: 1.2:1 (y)
    Channel #20: 1.1:1 (y)
    Channel #40: 1.0:1 (y)

    I think I could fool around and fool around but this is about as practically close as it's going to get and so far with the feed point only about 6ft. off the ground I've gotten some good reports.

    Thats all for now. Next step is an antenna raising. ;)

    John
     
  15. HomerBB

    HomerBB Sr. Member

    Joined:
    Jan 4, 2009
    Messages:
    3,781
    Likes Received:
    2,167
    Great!

    How high you gonna put it?
     

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!