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How do this homemade loft find antenna work ??146mhz

Discussion in 'Amateur Radio Antennas' started by davev8, Jan 13, 2021.

  1. davev8

    davev8 Gold Star/Marvin Award Member

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    this was posted on my FB page i will cut and paste my FB reply which abit of a description and my thoughts but you need to see the photos in the link to the original article below but what i am asking what type of antenna is it and how do it work any links to articles about this antenna would be handy ................................................it is interesting ...reading the text it appears that the vertical stub don't touch the main radiator so not like a j pole ..the coax that go up the center of the tube the center of the coax is connected to only the stub that is not connected to the main tube ..the brade is connected to the main tube...so i guess the stub must be capacitively coupling to the main radiator like the inner rod on a gamma match don't physically touch the outer tube ...tonight i will ask on the world wide DX forum ..some clever bods on thier ...i have a feeling more maybe going on with this antenna than is 1st apparent.... EDIT i am guessing the radials are not ground radials but a captacant hat
    LINK
    https://ham.stackexchange.com/quest...Gb0TC25dfcxKcBn-kdDlq57cdtgmiZt3yyJZr4R4tZyjE



    Thanks dave
     

  2. bob85

    bob85 Supporting Member

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    its a homebrew direct fed j-pole with radials part way down the mast,

    a j-pole need not be shorted at the base of the stub & the coax tapped up the stub for 50 ohms, you can direct feed a j-pole like the one in the link,

    when you find the correct wire length & spacing for the tube & wire diameters you are using you will get a low vswr.
     
    midnight special likes this.
  3. davev8

    davev8 Gold Star/Marvin Award Member

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    i see so is a type of j pole ...so what's the idea of the extended pole below the feed point and the radials ?
     
  4. bob85

    bob85 Supporting Member

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    you see all sorts of strange ideas with homebrew antennas, i imagine they were trying to keep currents off the coax braid.
     
    binrat likes this.

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