How important is the wire gauge for counterpoise?

Discussion in 'Ham Radio Discussions' started by CA3FJK, Mar 10, 2021.

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  1. CA3FJK

    CA3FJK Premium Subscriber QRZ Page

    I may be stirring up the hornet's nest but let's see how it goes.

    I like endfed antennas and usually in the field I don't use an "explicit", dedicated wire as counterpoise.
    I'm looking to optimize my compromised QTH EndFed antenna by adding a counterpoise wire (I already have a choke balun outside the shack).

    The length I'm looking to add is 0.05 wave length of the lowest frequency, which is 40m. that would be 2 meters or 6.56 ft. Reference: https://zenodo.org/record/1099140/files/10000459.pdf

    so the question is how important is the wire gauge for an EndFed (9:1) (shortened with loading coil not EFHW) 100w antenna?

    will a 24 AWG be enough? (that's the same wire I use for antenna building so that's the one handy in 500m spool)

    looking forward for the feedback.

    Fernando
     
  2. WA9SVD

    WA9SVD Ham Member QRZ Page

    Mechanical strength requirements are probably the most important.
     
    W4IOA, W0FS, N1YR and 4 others like this.
  3. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Go for it.
     
  4. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    Add ten or twenty of them and your antenna efficiency will improve a good deal.
     
    WA9SVD likes this.
  5. WZ7U

    WZ7U Ham Member QRZ Page

    Implement elevated radials and you need less, much less. Like four.
     
    KD1JT, KA4DPO and N7WR like this.
  6. W0FS

    W0FS Ham Member QRZ Page

    i don't believe current flow is much of a concern in a counterpoise wire, especially at 100 watts. As somebody said, the main concern would probably be breaking strength. In 6'+ of wire, you're not going to have much wind or ice load.
     
    KU3X and CA3FJK like this.
  7. W7HV

    W7HV Ham Member QRZ Page

    Resistivity losses are losses whether they occur in the antenna or a counterpoise (or in ground losses in trad verticals). It's your RF being converted to heat. With an end-fed antenna, the feedpoint is at a very high impedance point, which mean the voltage is high and current is low so a small diameter counterpoise should be OK loss-wise, though 24 awg is pretty thin. It'll work, but personally I'd go at least 22 or 20.
     
  8. W4NNF

    W4NNF XML Subscriber QRZ Page

    As SVD says, really just a mechanical consideration.
     
  9. N1BCG

    N1BCG Ham Member QRZ Page

    Do you have a 9:1 balun at the feedpoint and coax running to the shack or is the coax connected to the end-fed antenna with a choke balun close to the shack?

    It's common to add a short counterpoise to Zepp antennas fed with open wire feedline because the feedpoint can't be of an infinite impedance as suggested by one lead of the feedline left unconnected. A short counterpoise is commonly used in this case.

    Your situation would be similar if you had a 9:1 balun at the feedpoint which allows the use of coax instead of an open wire feedline.
     
    CA3FJK likes this.
  10. CA3FJK

    CA3FJK Premium Subscriber QRZ Page

    I have the unun at the feedpoint then a run of coax to the shack, outside it a 1:1 choke balun, then a patch cord to the radio.
     

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