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My inverted V

Discussion in 'CB Antennas' started by Pman62, Dec 3, 2020.

  1. Pman62

    Pman62 Member

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    I made an inverted V dipole complete with home brew BALUN and it has been performing beyond my expectations. It was just an experimental antenna, but now I would like to mount it permanently because it just works great. Now my question is: presently it is made of stranded 16 AWG insulated wire. Will this hold up? Or should I replace this with either hard drawn or copperweld type wire? Any thoughts?


     
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  2. Crawdad

    Crawdad Well-Known Member

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    To me homebrewing an antenna system that works well is as good as it gets. I will never buy an antenna again, they're too easy to build. I also put up an Inverted V (with #12 MTW), brewed a 1:1 toroid choke for it and it turned out great. Less QRM and I have to look close @ the SWR meter to see if the needle moved. Also has great bandwidth. Have a wire Moxon on the drawing board now.
    Depending on your QTH, how much ice and wind you get will probably determine how well it holds up. If your connections are solid, strong and sealed, it should be good for quite a while. Even if you loose it to weather it will be relatively easy to replace with a beefed-up version.

    73
     
  3. groundwire

    groundwire Sr. Member

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    Agreed. If its free from tree limbs etc from hitting it and breaking it, and you keep your output power down, 16 guage wire will be fine.
     
  4. W1AFG

    W1AFG Member

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    I use #12 stranded on my projects and it seems to work fine. Currently i have a homebrew 100' center fed dipole which has been in service for at least 10 years without a hitch.
     
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  5. M0GVZ

    M0GVZ Sr. Member

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    I prefer stranded, it has more give.
     
  6. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    Yes stranded is much easier to work with
     
  7. Pman62

    Pman62 Member

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    My only concern is the wind we deal with very often around here. This wind is compounded by the fact I live way out in the country on a farm, which equals a lot of flat land with no obstructions to mitigate the wind. In fact, I have thought a lot about putting up an electric generating wind mill or two.
     
  8. Crawdad

    Crawdad Well-Known Member

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    You know best what your situation is. Solid copper doesn't do as well in heavier winds, stranded flexes more before breaking. I have no experience with Copperweld but it is doubtless very strong. Heavier gauge wire with good strong connections may be where you need to go. If you go up in wire size you may need to retune (shorten the elements slightly). How difficult it is to replace your wires if they fail will dictate what type to use. Let us know how it turns out.

    73
     
  9. M0GVZ

    M0GVZ Sr. Member

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    My 80ft long inverted L with a 55ft long horizontal section was made from stranded wire. We're exposed to westerly winds and it was orientated north/south. Several winter storms a year where wind speeds would get up to in excess of 70MPH and it lasted just fine.

    THe furthest end wasn't actually fixed to anything. It went to within a few feet of a pole attached to the back of the house with a pulley on. I put a loop on the end of the antenna wire, attached a long length of paracord to the loop which was fed through the pulley and was long enough to reach the ground. On the end of the paracord I put a plastic 2L drinks bottle which I filled so far in order to keep the wire tensioned. Because the far end of the wire wasn't fixed it allowed it to move if needed depending on the wind.
     
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  10. Pman62

    Pman62 Member

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    Another thing I have forgotten about! Giving a wire antenna a little "give" by either springs, or the counter-weight system you described. I guess I'm getting old
     
  11. CherokeeSoccer

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    Just getting back into radio after many years away. I keep hearing about these inverted dipoles and I’m really interested in building one. Something I’ve noticed in my research is that many discussions aren’t informative for someone like myself that has no idea where to start. They assume the reader already knows the basics. Things I’m having a difficult time understanding are how and where these wire antennas are fed with coax and what the rx and tx are affected by length. Are baluns a must to attain the best swr possible? Can you, or anyone else recommend a good source for me to learn from?
     
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  12. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    The simplest thing you can do isget an 8' extension cord, split than wires apart, spilt your coax and attach the center conductor to one wife and the other wire to the shield. It really is that easy.
     
    #12 w9cll, Dec 9, 2020
    Last edited: Dec 9, 2020
    CherokeeSoccer likes this.
  13. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    Dang autocorrect
     
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  14. Crawdad

    Crawdad Well-Known Member

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    Lots of info out there, just Googlize "Inverted V Dipole antenna". Nothing super special about them, I use one because of space restrictions (balcony). It's just a 1/2 wavelength centerfed horizontal dipole with the element ends moved downward like an upside down "V".

    Easy to calculate element lengths, 468/your freq-of-choice will give you total wire length (both "poles" or 1/2 wavelength) in feet, 234/your freq-of-choice will give you the individual element length (each "pole" or 1/4 wavelength). Those calculated lengths should give you more wire than you need but it doesn't hurt to cut a little longer so you have enough for attachment and/or tuning.

    Probably the minimum feedpoint height for decent lower angle signal propagation (DXing) is 1/2 wavelength above ground or about 18' @ 27MHz. Much lower than that and your radiation mostly goes up instead of out.

    A horizontal dipole is supposed to have a feedpoint impedance of 72 ohms so they can be fed with 50 ohm coax. When you lower the ends to make the "V" the impedance gets closer to 50 ohms (good SWR). Best not to go beyond a 90 degree angle in the "V" (from the 180 degree horizontal) or the impedance begins to climb and the elements begin to interact. Try to run your feedline perpendicular to the elements for as far as possible to avoid it coupling and becoming part of the antenna.

    Feeding a balanced antenna (dipole) with an unbalanced feedline (coax) can some times cause current to run on the outside of the coax shield (Common Mode Currents) which can cause radiation pattern distortion, noise and RFI problems so it's not a bad idea to have some type of RF choke @ the feedpoint to block the Common Mode, but there are lots of antennas out there working fine without one. If needed a 1:1 RF choke made with a ferrite toroid ring is inexpensive and easy to homebrew (more Googlizing for you). Depending on who you ask a 4-5" dia. coil of coax at the feedpoint also works.

    An inverted v radiates a mostly horizontally polarized omni-directional signal. Ok, I'm typed out.

    73
     
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  15. CherokeeSoccer

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    That was very helpful. Thanks!
     

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