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Thread: Best 14dbi flat?

  1. #1
    FPV Addict Scotttu's Avatar
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    Best 14dbi flat?

    DPCav doesn't carry a 14dbi flat patch and there's a lot of riff raff from China.

    What brand do you recommend?

    Or do I go with a Yagi?

    I want to attempt a lengthy flight next weekend and my 8dbi probably won't be enough (10 miles).
    "Truly superior pilots are those who use their superior judgment to avoid those situations where they might have to use their superior skills"- Author unknown

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    Team Blacksheep FPVflyer's Avatar
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    Which frequency?

  3. #3
    FPV Addict Scotttu's Avatar
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    2.4ghz
    "Truly superior pilots are those who use their superior judgment to avoid those situations where they might have to use their superior skills"- Author unknown

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  4. #4
    Engineer for Jesus Christ IBCrazy's Avatar
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    Avoid the Yagi antenna. The sidelobes are a killer.

    To me you have 2 realistic options:

    1. Guess - You can buy one from China and send it to me for testing. I will mail it back to you with the results.
    2. Buy a BiQuad. You can get one from Urban Drones. When I fly linear polarization, I use a BiQuad.

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

    videoaerialsystems.com - Performance video piloting

  5. #5
    FPV Addict Scotttu's Avatar
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    Is a bi-quad going to get me out to 12 miles ?

    For that matter is my 8dbi? (Probably not?)

    Where I'm going should be very clean from outside interference...
    Last edited by Scotttu; 22nd May 2012 at 11:33 AM.
    "Truly superior pilots are those who use their superior judgment to avoid those situations where they might have to use their superior skills"- Author unknown

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  6. #6
    Engineer for Jesus Christ IBCrazy's Avatar
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    It depends on your noise floor and transmit power, but 12 miles on a BiQuad shouldn't be too hard. Theoretically speaking, a BiQuad is good for 25 miles on 1 Watt transmiting power.

    A Yagi will do great once you get out a good distance. However when at mid-range, it tends to go nuts due to the side lobes.

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

    videoaerialsystems.com - Performance video piloting

  7. #7
    Team BlackSheep Trappy's Avatar
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    From personal experience, after 5-6 miles TBS brings out the heavy artillery. 19dbi yagi is good for 20 miles. a 16 or 18dbi patch might be a good place to start. I haven't tested IBCrazy's BiQuad suggestion but judging from his experience it will be a very good way to go. remember, when you fly 5 miles, get an antenna that can do 20. When you fly 10 miles, the antenna should do 40. If you've watched our long range flights you will see that once you're reaching an antenna's limits the picture comes and goes as it pleases.

    Oh, and get a qualified spotter. By qualified I mean he needs to know what the ***** he's doing practice with him first before sending 2 grand 10 miles away into harms way.

  8. #8
    KK4IRW MASHTON1138's Avatar
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    Quote Originally Posted by Trappy View Post
    Oh, and get a qualified spotter. By qualified I mean he needs to know what the ***** he's doing practice with him first before sending 2 grand 10 miles away into harms way.

    You know Trappy I really think you guys are great, pushing the limits of equipment and rules and regulations. I have almost always been impressed with the advice you give guys as it is good stuff. But that was the absolute best advice I think you have ever given. It should be a sticky on TBS's website.
    Quote Originally Posted by whakahere View Post
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  9. #9
    Engineer for Jesus Christ IBCrazy's Avatar
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    ^Good advice. The problem with high gain is sidelobes and why I recommended the BiQuad. The only lobe it has is a small one in the rear. When it's ready to drop out, it gives a good warning. If you look at a Yagi radiation pattern, you will see sidelobes that tend to be picked up causing video drop outs when there is plenty of distance left. This is the real challenge with a Yagi: knowing when you're about to go too far.

    Another thing to remember: how well you can aim your antenna. This is the real job of a good spotter. BiQuads are the easiest to aim if aiming based on video clarity. yagis don't do well here. However if your spotter has a good map and can read it, go for the real high gain stuff and go for it. A BiQuad is only 11 dbi. A double BiQuad is 13dbi. You can make these yourself relatively easily.

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

    videoaerialsystems.com - Performance video piloting

  10. #10
    Team BlackSheep Trappy's Avatar
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    Quote Originally Posted by MASHTON1138 View Post
    You know Trappy I really think you guys are great, pushing the limits of equipment and rules and regulations. I have almost always been impressed with the advice you give guys as it is good stuff. But that was the absolute best advice I think you have ever given. It should be a sticky on TBS's website.
    haha thanks. I can't stress this enough, though. if we could put a "qualified spotter" in our shop, we'd do it right away

    Quote Originally Posted by IBCrazy View Post
    ^Good advice. The problem with high gain is sidelobes and why I recommended the BiQuad. The only lobe it has is a small one in the rear. When it's ready to drop out, it gives a good warning. If you look at a Yagi radiation pattern, you will see sidelobes that tend to be picked up causing video drop outs when there is plenty of distance left. This is the real challenge with a Yagi: knowing when you're about to go too far.

    Another thing to remember: how well you can aim your antenna. This is the real job of a good spotter. BiQuads are the easiest to aim if aiming based on video clarity. yagis don't do well here. However if your spotter has a good map and can read it, go for the real high gain stuff and go for it. A BiQuad is only 11 dbi. A double BiQuad is 13dbi. You can make these yourself relatively easily.

    -Alex
    correct. the 30 mile flight was our first really long range flight. we found out later that we were flying it on a side-lobe of the 24dbi grid. the way we found out was when RiSCyD landed he looked at the antenna and said "hey man, we're flying over there" I had pointed the antenna about 15 degrees away from our landing spot 30 miles out.

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