How does that J-pole really work?

Discussion in 'Amateur Radio News' started by AF7NX, Oct 28, 2020.

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  1. AF7NX

    AF7NX XML Subscriber QRZ Page

    The ubiquitous J-pole is not them most intuitive antenna in the world. Gary Rondeau, AF7NX, explores the J-pole using the 4NEC2 modeling program to shed some light on this common design.
    Modeling the J-pole
    SA6CKE likes this.
  2. KX4O

    KX4O Ham Member QRZ Page

    Nice info.

    The Wikipedia page on the J-Pole is in pretty good shape, mercifully short (encyclopedic), exceptionally well referenced (for a Wikipedia article), and is the goto place to learn past and current details.

  3. WL7PM

    WL7PM Ham Member QRZ Page

    Interesting read at the WIKI link.
    Apparently 6 pounds of copper pipe can be made to radiate, but there is NO advantage over a 19 inch long vertical piece of 12 gauge bare copper wire.
    KR3DX likes this.
  4. KM1H

    KM1H Ham Member QRZ Page

    It sounds like a VHF version of the Double Bazooka dipole, lots of smoke and mirrors. I built one decades ago from 450 Ohm ladder line and hung it indoors from an attic roof rafter to access the old DX cluster and some friends on Simplex. It did the job but my hilltop location did most of the work.

    A ground plane for 2M (and 135 cm) was built from PVC plumbing parts and #10 solid, I didnt have any 12 handy. They were mounted just above the roof line, about 6' apart, and far outperformed the J in many Simplex comparisons during VHF contests.

    KR3DX likes this.
  5. KD8DEY

    KD8DEY Ham Member QRZ Page

    End fed Zeppelin antenna....

    Dont ask what you can do with a J-pole
    Ask what a J-Poler can do for you
  6. KX4O

    KX4O Ham Member QRZ Page

    Two potential advantages of the typical J over 1/4 wave GP:
    • Slightly higher gain... not much, but measurable and repeatable.
    • Robust DC ground antenna design.
  7. KF4ZGZ

    KF4ZGZ Ham Member QRZ Page

    For my location a 2m ground plane has always outperformed j-poles exponentially.
    KR3DX and KM1H like this.
  8. KM1H

    KM1H Ham Member QRZ Page

    If one person started selling all the snake oil antennas under one name he could get real rich real fast. Add "Miracle" to the names for another boost.
    KR3DX likes this.

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