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Thread: Using a Dipole As An Upright

  1. #1

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    Default Using a Dipole As An Upright

    I had an idea to use my 10 meter dipole as an upright. If I put one leg up a tree, and the other out to the side as a ground plane, from my understanding I will have made a quarter wave upright. I am asking as much as stating. If anyone has done this please share your experience. Also making this adjustment, i should remain at 50 ohm resistance and have no need for an unun/unbal. any input on these thoughts are appreciated.

    KD9KVS

    I have a brain injury.
    I am not my brain injury.
    This does not define me.

    P.S. I appreciate all the input, for some reason my responses are not being approved. but they are coming once the button is clicked.
    Last edited by KD9KVS; Sat 20th Apr 2019 at 14:05.

  2. #2

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    May I suggest you will have better luck if you add at least two (or three) more 1/4 wave counterpoise elements evenly spaced around center, horizontally at the base. Not that what you propose won't work, it's just that you will get a more omni directional pattern from your RF output. This is commonly known as a 1/4 wave ground plane vertical, which is what you are proposing here. You shouldn't need any sort of UNUN/BALUN for this to be efficient, however the impedance will be slightly less than 50Ω, probably around 35Ω or so. You can bring the impedance back to around 50Ω by tilting the ground plane elements downward between 30 and 45. At least that's been my experience with the 40 meter 1/4 wave ground plane I put up here in CN86jc using 12ga wire and a big bamboo sprig. Check out my zed page for a less than stellar view of what I did. https://www.qrz.com/db/WZ7U I really should put up a clearer picture some day...

    Try these resources -
    https://m0ukd.com/calculators/quarte...na-calculator/

    http://www.csgnetwork.com/antennagpcalc.html

    http://www.dx-antennas.com/Ground%20plane.htm

    Bookmark them so you can refer back as needed. Hope this helps, I'm sure YouTube has a few videos about it as well. Let us know how it goes OM. 73!
    Last edited by WZ7U; Fri 19th Apr 2019 at 09:27.

  3. #3

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    Quote Originally Posted by WZ7U View Post
    May I suggest you will have better luck if you add at least two (or three) more 1/4 wave counterpoise elements evenly spaced around center, horizontally at the base. Not that what you propose won't work, it's just that you will get a more omni directional pattern from your RF output. This is commonly known as a 1/4 wave ground plane vertical, which is what you are proposing here. You shouldn't need any sort of UNUN/BALUN for this to be efficient, however the impedance will be slightly less than 50Ω, probably around 35Ω or so. You can bring the impedance back to around 50Ω by tilting the ground plane elements downward between 30 and 45. At least that's been my experience with the 40 meter 1/4 wave ground plane I put up here in CN86jc using 12ga wire and a big bamboo sprig. Check out my zed page for a less than stellar view of what I did. https://www.qrz.com/db/WZ7U I really should put up a clearer picture some day...

    Try these resources -
    https://m0ukd.com/calculators/quarte...na-calculator/

    http://www.csgnetwork.com/antennagpcalc.html

    http://www.dx-antennas.com/Ground%20plane.htm

    Bookmark them so you can refer back as needed. Hope this helps, I'm sure YouTube has a few videos about it as well. Let us know how it goes OM. 73!
    Okay, kind a rough day with my brain. so please excuse mistakes and such. I have seen where others have done the leg thing as well. It is good to have direct input from someone who has messed with this and found the best way. I appreciate this input. some of my line of thinking was to figure out if there was a way to take a simple dipole and create a vertical with approximately 50ohms resistance. one thing iv thought of is what if the legs are different lengths, but still resonant. ie 16' up, 8' burried underground a couple inches as a ground plane. something that could be thrown up in nature with little to no effort. God bless and good day. 73s

    KD9KVS


    I have a brain injury.
    I am not my Brain injury.
    This does not define me.

  4. #4
    M0WAO's Avatar
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    73 de Biton - m0wao - echolink 633710
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  5. #5

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    Quote Originally Posted by M0WAO View Post
    That does look really close to what I had in mind. It almost appears they set that up similar to a J-pole. i wonder if that helps to keep it at 50 Ohms.

  6. #6

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    There's nothing new about vertical dipoles.
    Just few suggestions:
    The higher from the ground the better.
    Run the coax away from the feed point at 90 from the vertical for as long as practically possible
    or if you're using tubing, run the coax /through/ the lower element.

    Virtually every book about aerials for amateur radio will cover using dipoles vertically polarised.

  7. #7

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    What they're suggesting is that you don't really do what you said because it simply doesn't work very well.

    If you have a ten metre dipole, this usually means it's 2.5m up from the centre conductor, and the screen goes down 2.5m - so top to bottom, 5m or close to this. It works pretty well with an omnidirectional pattern. If you bring up the bottom leg then you have removed the balanced element of the design, and it needs a proper ground plane to give the omnidirectional pattern. Raising the bottom creates a very, very poor ground plane, so your omni pattern will be a very strange shape rather than round, with lobes creating better performance in some directions, and terrible ones in another. The removal of that bottom element from vertical also buggers up the impedance, lowering the power available again, and probably increasing the interference you create. If you mount the vertical on the ground performance gets better, and if you cannot do that, the idea to add in multiple 1/4w horizontal elements starts to re-create the ground plane up in the air. However, you really need to try this out, moving things, checking VSWR then moving again or adding etc. A field strength meter is very handy because going around the antenna at say 10m distance will show you which direction the RF is going (or not!)

  8. #8

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    Quote Originally Posted by paulears View Post
    What they're suggesting is that you don't really do what you said because it simply doesn't work very well.

    If you have a ten metre dipole, this usually means it's 2.5m up from the centre conductor, and the screen goes down 2.5m - so top to bottom, 5m or close to this. It works pretty well with an omnidirectional pattern. If you bring up the bottom leg then you have removed the balanced element of the design, and it needs a proper ground plane to give the omnidirectional pattern. Raising the bottom creates a very, very poor ground plane, so your omni pattern will be a very strange shape rather than round, with lobes creating better performance in some directions, and terrible ones in another. The removal of that bottom element from vertical also buggers up the impedance, lowering the power available again, and probably increasing the interference you create. If you mount the vertical on the ground performance gets better, and if you cannot do that, the idea to add in multiple 1/4w horizontal elements starts to re-create the ground plane up in the air. However, you really need to try this out, moving things, checking VSWR then moving again or adding etc. A field strength meter is very handy because going around the antenna at say 10m distance will show you which direction the RF is going (or not!)

    This is very informative, and I appreciate it. I had replied to some of the other statements as well, and could not figure out why they were not posting. Somewhere between me writing this and now I got instant post approval. All that being said...

    What I am drawing from all of this is that it will work, just not well without modification that therefore changes the style and of the antenna to something that is no longer a balanced antenna. SO, it sounds like I'd be better off using my magna-mount on a steel plate, that is ground, and mounted as high as I can convince someone to take it? Until I am able to build/buy something better. The lot we live on is oddly shaped and 3 of 4 yards are considered front yard, and have electric wires running the perimeter. my dipole is only at fence height, and the house is only feet from that, with metal siding. I am truly considering running my cable to the least driven vehicle, sticking the antenna on to it, and seeing what I get. I was dxing from Washington D.C. with my antenna (magna-mount) sitting at my door jam inside. I am excited to get talking with this new radio, so much more to learn. or maybe relearn. Either way I am excited. God bless and good day, 73s


    KD9KVS


    I have a brain injury.
    I am not my brain injury.
    this does not define me.

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