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Thread: inverted V uhf

  1. #11
    Navigator FPV-PLASTICS's Avatar
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    Quote Originally Posted by syscons View Post
    Would it be best to mount those V antennas like Dipoles, so one end pointing up on the Wing and one down?

    How do they compare to a Dipole? Would be nicer to mount on a Wing..
    hi

    the way matt mount hi antenne in post 3 that rocks

  2. #12
    Navigator FPV-PLASTICS's Avatar
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    Last edited by FPV-PLASTICS; 7th May 2013 at 02:47 PM.

  3. #13
    Engineer for Jesus Christ IBCrazy's Avatar
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    @Rob - Mind your polarization. Remember to tell people your Vees are horizontally polarized when mounted like that.

    I like your style. This is better to have a counterpoise and they're easy to mount.

    -Alex
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  4. #14
    Navigator FPV-PLASTICS's Avatar
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    Quote Originally Posted by IBCrazy View Post
    @Rob - Mind your polarization. Remember to tell people your Vees are horizontally polarized when mounted like that.

    I like your style. This is better to have a counterpoise and they're easy to mount.

    -Alex
    Hi alex

    You mean whit 6 gram you don t have a CG problem??

    I like the 6 gram and flex spring steal

    when your plane go nose down in the ground
    The 6 gram ant don t rip out the sma from uhf rx

  5. #15
    Navigator FPV-PLASTICS's Avatar
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    Quote Originally Posted by IBCrazy View Post
    @Rob - Mind your polarization. Remember to tell people your Vees are horizontally polarized when mounted like that.

    I like your style. This is better to have a counterpoise and they're easy to mount.

    -Alex
    dubble post,,,my cellfoon did that???
    Last edited by FPV-PLASTICS; 11th May 2013 at 10:39 AM.

  6. #16
    Engineer for Jesus Christ IBCrazy's Avatar
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    Rob,

    For your feedline put this bead on it to balance the antenna and get a uniform radiation pattern: http://www.digikey.com/product-searc...ds=240-2067-nd

    This will keep the signal from tracking back down the outside of the cable shield. It fits perfectly over RG316 coaxial cable.

    I am curious what kind of spring steel you are using? Most spring steel is difficult to solder.

    -Alex
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  7. #17
    Navigator FPV-PLASTICS's Avatar
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    Quote Originally Posted by IBCrazy View Post
    Rob,

    For your feedline put this bead on it to balance the antenna and get a uniform radiation pattern: http://www.digikey.com/product-searc...ds=240-2067-nd

    This will keep the signal from tracking back down the outside of the cable shield. It fits perfectly over RG316 coaxial cable.

    I am curious what kind of spring steel you are using? Most spring steel is difficult to solder.

    -Alex
    hi alex that,s for tips

    for ant whit coax,,yes i can order some ferrit kern
    never now where is for
    whit fine tune the uhf antenne the analyzer say it,s oke

    about the spring steal soldering

    i find some soldering [ tin ] from 10 jears old
    you can,t buy it anymore ,, not save,,jears ago they soldering water pijps whit it

    this tin i have soldering real good on steal

  8. #18
    Engineer for Jesus Christ IBCrazy's Avatar
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    Hmm... Good to know. Most solder I know is 40% tin and 60% lead. I just learned how to solder stainless steel using phosphoric acid. Apparently a 50/50 mixture of alcohol and phosphoric acid allows just about anything to be soldered together. The guy who showed me used potato vodka as the alcohol source. I'm not sure what the alcohol is supposed to do but I know the phosphoric acid etches the metal. This might be a good solution should you run out of your solder.

    The reason for the ferrite bead is to help with what we call "skin effect". High frequencies travel down the outside of a wire. For a #0000 wire, only 125Hz is required for less than 100% skin depth. For a 22 AWG wire, all you need is 100kHz and almost all of the current rides on the outside of the wire. At our frequencies, the effect is so large that you can actually have a reverse current from the inside of the wire than you do on the outside of the wire. Think about the cable shield. You have a signal inside it, but skin effect causes a current along the outside of the cable. This causes the cable shield to act as a resonator and will throw off the radiation pattern which as you know is the most important thing to an antenna.

    The way to fix this is you need to "choke" the cable. in other words, you need to increase the resistance of the shield to RF. One way to do this is to coil it up in a toroid. This works by turning the cable into an inductor. This is unfortunately bulky. However if we use a ferrite bead thngs get easier. Think of a it as a 1/2 turn transformer. The magnetic field couples with the ferrite and attempts to magnetize it. Since the relative permeability of the ferrite is to the order of 200 or more, this looks like a 100 turn inductor! This makes the impedance of the line go from a few hundred ohms to a few thousand! problem solved

    -Alex
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  9. #19
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    very very interesting. Does this ferrite ring have a good effect on all antenna's? I mean does it work for transmitter AND receiver antenna's?
    Why aren't we using this on all cloverleaf antenna's? because if it improves radiaton pattern, why are we not using it? Or is it not for high frequencies like 5.8, and only for 433MHz....?

  10. #20
    Navigator FPV-PLASTICS's Avatar
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    hi guys

    good question elmar

    do we need ferrit on clovers to

    here my work from today

    they are from spring steel,,real hard to make then
    they are for myself,,i don,t sell stuff that,s no my idea or it,s must have a great mod


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