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Radials question.. 120 or 60, difference?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KF7QEC, Nov 21, 2018.

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  1. KF7QEC

    KF7QEC Guest

    Hi all,
    I've decided on the vertical I am going to put up in the spring, going with a Zerofive 43' 10-160 multiband. I certainly have the room for it, but I do have a question about radials. The manual says:

    "Your ground radial system is the most important part of vertical antenna performance. When installing ground-mounted radials use radial lengths between 20 and 43 feet, with 43 foot being the choice for best performance. If you have to use shorter length radials, put more down. A good place to start is a minimum of 32 with 120 being the best."

    I have room for 120, 43' foot long radials. I figure based on a circle radius of 43' from the mast, the circumference should be 270.18'... divide that by 4 (four sides of the radial plate), the end equation shows that the radials should be spaced 27.18 inches apart (30 radials per 1/4th of plate) at the circumference of the circle. That seems manageable, but I am curious how much my sending and receiving signal would be compromised if I used half as many radials (60), spaced 54.36 inches apart. Half as much copper down on the earth.

    This is my first vertical and would appreciate any advice.
    Thank you,
    Orion, KF7QEC
    Troy, Idaho
     
  2. N4UFO

    N4UFO Ham Member QRZ Page

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  3. K7TRF

    K7TRF Premium Subscriber QRZ Page

    It's likely you wouldn't notice any difference at all. A set of 60 evenly spaced ground radials, each 43' long in a full circle around the feed point is a very good field of radials. Sure doubling that will have no downside except time and expense but I doubt either your receive or transmitted signals would be measurably different with 'only' 60 radials. I'd personally lay down the 60 radials and operate the antenna for a while. You can always lay down the remaining 60 if you feel you're missing something but I doubt you'd be able to tell the difference.
     
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  4. KF7QEC

    KF7QEC Guest

    I was hoping that would be the answer. Thank you!
     
  5. KA2RRK

    KA2RRK Platinum Subscriber Platinum Subscriber QRZ Page

    Do not break the bank account. Put down a few thousand ft of radials. You will be fine.
    Your after a stable impedance during all operating conditions. It is not how long but rather how many.



    KA2RRK
     
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  6. KA2RRK

    KA2RRK Platinum Subscriber Platinum Subscriber QRZ Page

    Agreed.

    KA2RRK
     
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  7. KA2RRK

    KA2RRK Platinum Subscriber Platinum Subscriber QRZ Page

    I stopped @ 1200. As I was getting almost out of stock on Bell wire.

    KA2RRK
     
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  8. AA3EE

    AA3EE Ham Member QRZ Page

    30 to 36 is where you reach the point of diminishing returns. I think from 36 to 120 you gain .5 dB.
    Go through the N6LF material. There's two ways to go: buy lots of wire and figure out how many/how long, or pick a number and figure out how long they should be. IIRC, there's a sort of magic number for the end spacing in wavelengths like .08 wavelengths.
    This is all for single band use, I'm not sure what you should do for multiband. Maybe design it for the lowest band?

    http://www.w0btu.com/Optimum_number_of_ground_radials_vs_radial_length.html
    http://ncjweb.com/bonus-content/k3lcmaxgainradials.pdf
     
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  9. NH7RO

    NH7RO Ham Member QRZ Page

    OK, Here's mine:

    Go to the extra trouble of sinking a sturdy non-metallic post into the ground so that you can mount your ZeroFive atop it. Elevated, say, five to ten feet above ground it will slightly improve performance and drastically reduce the number of radials needed.

    N6LF determined that 4 elevated radials 4 feet above average ground and tuned for the band in use==the same antenna ground mounted with 120 ground radials (more or less). Kind of an amazing difference, hey?

    I mention this since I seem to recall that you live out in the boonies---in Idaho---where you might actually be able to implement something like this. I've often dreamed of building a wooden tower or observation deck out of 4x4 posts where I could mount a really effective Marconi; but that dream will have to wait until I someday leave our little condo on the golf course before becoming a definite possibility.

    Length can vary between 0.15 and 0.40 wave length and due to variations in the ground said antenna is mounted over as well as other factors such as SWR bandwidth that while 2-4 radials is fine, 16 elevated radials is optimum. If you do end up doing this, aim for a radial height of 7 feet or more so animals and people don't get caught underneath. (I have my radials around 5-6 feet above ground here and a couple have gotten snagged by an occasional deer antler but so far it is'nt too much of a problem for me to replace them)

    While there is no free lunch in any antenna system there are occasional bargain benefits such as this and I hope you give the idea some consideration.

    Have fun!

    73,

    Jeff
     
    Last edited: Nov 21, 2018
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  10. AJ6O

    AJ6O Ham Member QRZ Page

    I have 32 radials 33 feet long on my 40 meter ground mounted Zerofive vertical, and it works fantastic. I plan on installing at least 15 more, but I doubt if I will notice any difference based on many articles I have read. Going from 8 to 16 radials shows the biggest increase in performance.
    Going from 32 radials + does increase efficiency but very minutely.
     

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