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Copper wire antenna free space gain,

Discussion in 'Home Brew' started by cbkidd1, Jul 12, 2019.

  1. cbkidd1

    cbkidd1 Active Member

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    I want to build a copper wire antenna. And was wondering if there a way to increase the dBi free space gain? By making the wire longer or by some other means that would that increase the dBi? Are there any books that go into detail about how to increase free space gain of copper wire antennas? I appreciate any help I could get on this topic. 73,


     

  2. Road Squawker

    Road Squawker Sr. Member

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    ARRL antenna book

    AS a general rule, adding length will tend to develop lobes that focus the power in certain directions at the expense of other directions.https://ftp.unpad.ac.id/orari/libra...ant/docs/Introducing the All-Band Doublet.htm



    This is not actual "gain" per se, it is "directivity".
    You can also add radials (for efficiency).
    change the conductor diameter..
    ect,ect,ect.
     
    Shadetree Mechanic and The DB like this.
  3. sp5it

    sp5it Master of puppets

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    What kind of antenna, what band/freq?
    To increase gain you can change shape, make array, phase, stack etc.
    Mike
     
  4. The DB

    The DB Sr. Member

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    The recent versions of the ARRL Antenna Book talked about wire antennas, any thing from 15 edition on should be fine, and likely the versions before that as well. They don't refer to the gain of these antennas in free space, pretty much no one does, so I am curious as to why you asked about this?

    I guess the better question is what are you trying to achieve?


    The DB
     
  5. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    Zepp,,double extended zepp etc etc.
    As mentioned in previous posts is does not increase "gain" it just re directs the signal into a tighter lobe at the expense of adding nulls in other areas.
    Bobtail curtain, half square, just a few off the top of my head.
     
    Shadetree Mechanic likes this.
  6. kopcicle

    kopcicle Sr. Member

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    buy the book , make the movie...

    page284-page-001.jpg

    So once again let us go back to school...

    Imagine a point (RF) source.
    This source is located within a sphere at its center.
    The surface of the sphere is defined as unity gain.
    This sphere is all the gain you have.
    There is no more.

    To get any gain in any direction other that unity it has to come from within the volume of the sphere.
    So any "gain" that you get was already there.
    It is just being taken form the volume of the sphere and reapplied elsewhere.
    Hopefully in a useful direction.

    Myself , I am more concerned with nulls.
    If I'm taking gain away from an elevation or direction I want to make sure it isn't from somewhere I want or need it .

    It's called the Antenna Handbook. You need a copy.

    School's out ...

    ad nausea

    The feed point impedance of either of these examples will be on the order of several thousand ohms. You will need to investigate a "stub match" at the feed point to get it to a reasonable level for ladder or window line. Coax feed is not recommended.
     
    #6 kopcicle, Jul 14, 2019
    Last edited: Jul 14, 2019
  7. cbkidd1

    cbkidd1 Active Member

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    Thanks to everyone for there knowledge and explanations on wire antennas. I was thinking about maybe trying to build a wire antenna for talking DX. Instead of spending a lot of money on buying a beam. And started wondering if by making the wire antenna longer or making some kind of shape out of it or doing both. That you could raise the gain and not need to spend so much money on buying a beam. And have just as good if not better antenna? Just an ideal. 73,
     
  8. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    google up an N4GG array,, I built one for 11 meters and it was a surprise how well it worked long haul DX,

    http://ars.nc4fb.org/antenna-articles/n4gg1.pdf

    here is the link
     
    Rick330man likes this.
  9. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    Yah, yes the old Bobtail antenna...then I'll add the W8JK wire Beam plus add the LAZY H antenna:ROFLMAO:
     
    wavrider likes this.
  10. oldtymer

    oldtymer Active Member

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    Don't forget the Sterba Curtain.
     
  11. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    I never played with a sturba curtain, I did read about it on W8JI site, probably why I never played with one
     
  12. oldtymer

    oldtymer Active Member

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    they work, just a PITA to build
     
  13. Mudduckmobile

    Mudduckmobile Well-Known Member

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    You might find this fun. I did, and there's a lot of neat things to learn here.
    http://www.k7mem.com/Ant_Fat_Dipole.html
    "Fat Dipole" By Martin E. Meserve
     
  14. cbkidd1

    cbkidd1 Active Member

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    Wavrider, Thanks for the link. I own my own home so I don't need to worry about hiding anything. Unlike years ago when renting. I had one neighbor who called the FCC about my radio interference. That is something I will never forget lol. Thanks, Mudduckmod for the link. You are right there is a lot of info on this one. Nice to see I am not the only one that likes to try and build my own antennas. Both links are helpful. Wonder why no one gives the gain of the homemade wire antennas? 73,
     

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