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ASTROPLANE best vertical antenna ever?

Discussion in 'CB Antennas' started by nosepc, Oct 6, 2013.

  1. nfsus

    nfsus Member

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    What was the resistance and phase? Its neat to watch how it all changes with each adjustment


     

  2. nfsus

    nfsus Member

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    I didnt use a hat so I just extend or retract the upper stinger. Theres only so much you can adjust on these things unless you get creative. I'm thinking of getting creative though by making it where you can extend or retract the two lower legs but keep the hoop the same dia. If the numbers hold right then you could go into 20 meter band I'm thinkin. But im still thinking
     
    Alexis Mercado likes this.
  3. 43315

    43315 Member

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    Wow brings back memories. The first antenna I bought back around 1975 or so.
    Bought a astro beam and had better luck with the Omni.
     
  4. AudioShockwav

    AudioShockwav Extraterrestrial Admin
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    freecell likes this.
  5. freecell

    freecell Active Member

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    the astroplane antenna is a vertically polarized, off center shunt fed, end loaded and extended 3/4 wave dipole antenna, matched at level A using a full size quarter wave matching section. it is not colinear and it only functions as described above (and according to the manufacturers specifications) when element 14 (the "mast" section) approximates a half wavelength at the operating frequency or frequencies in question and only when any conducting support structure is insulated or isolated from the "mast" section.
     
    #605 freecell, May 13, 2021
    Last edited: May 13, 2021
    HomerBB likes this.
  6. The DB

    The DB Sr. Member

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    He clearly hasn't read the studies on this forum mostly by @bob85 and @Marconi with additional contributions from a few others on this forum, or it is possible that he read raid studies and didn't understand them, certain aspects of how this antenna actually functions take a certain understanding that goes far beyond the average technician. There are things happening with this antenna that I haven't seen happen in any other antenna out there such as the current distribution on the mast, or the part of the mounting bracket that is right next to the feed point yet appears at first glance to have no currents flowing on it in spite of the fact that there are peak currents flowing on both sides of said conductor. I can go on here.

    This really is a fascinating antenna, and I haven't seen very many people give an explanation that even understands that quirks and oddities even exist with this antenna, much less take any of them into account when describing how this antenna actually works. Typically, people just put this antenna into whatever category they feel it looks like or whatever info is found online that looks good at first glance, and go with that.

    I want to credit @bob85 and @Marconi specifically, as well as a few others, who have done a lot of work trying to figure out what is actually going on with this antenna design. I don't think they exactly agree with each other, but their opinions are going to be among the best out there.


    The DB
     
    #606 The DB, May 13, 2021
    Last edited: May 13, 2021
  7. Riverman

    Riverman Old Member

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    I’m a believer. Been a long time since I had one, but I seem to remember isolating mine using electrical tape and seeing an improvement in both receive and transmit.

    That said, I think the same holds true for any antenna. Seems to me a metal mast simply becomes a radial of some undetermined length which designers have no way to account for. Hence, it should not be allowed to become part of the antenna.
     
    freecell likes this.
  8. freecell

    freecell Active Member

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    the matching section aside, two thirds of the antenna wasn't in the box when you bought it. element 14 is the 1/2 wl. end of the dipole (below level A) and above level A is the other 1/4 wl. element forming the extended 3/4 wl. dipole, top loaded or not.
     
  9. HomerBB

    HomerBB Sr. Member

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    Interesting take on this. Perhaps someone will compare it to other 3/4ƛ antennas.
     
    freecell likes this.
  10. freecell

    freecell Active Member

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    they're all vertically polarized, off center, shunt fed (or not) and extended full wave dipole antennas, except for any real 7/8 wave models, which would be 1.125 wavelengths, all extended dipoles. an extended dipole for the sake of this discussion is any dipole in which one or both 1/4 wave elements are longer than a 1/4 wavelength, such as 1/2 wl, 3/4 wl., etc..

    https://www.worldwidedx.com/threads...ernative-view-point.31799/page-44#post-758740
     
    #610 freecell, May 18, 2021
    Last edited: May 18, 2021
  11. NorthStar

    NorthStar Administrator

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    I would love to try one of Coily's Astro Planes out one day to see how they perform.
     

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