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Thread: Airblade - Might be a new CP omni

  1. #1
    Engineer for Jesus Christ IBCrazy's Avatar
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    Airblade - Might be a new CP omni

    I was procrastinating a bit today and played with 4NEC rather than programming my foam cutter or my new CNC machine. I have been thinking about ways to minimize the impact of ground reflections on an omni directional antenna.

    What I came up with, was this: the Airblade. I basically took 5 biSquare antennas and placed them in a circle until the sine of the Z-components = 1. Thus it is pretty flat. I am thinking about changing the feed point to the middle of the square rather than the corner (need to get working on other projects).

    I'm getting decent simulation results with a .77 axial ratio. But the pattern is not symettrical which concerns me. However I open this thread up to anyone who wishes to build and experiment. Mind you, this is only a very early prototype right now, so I expect it to get better in later posts. I have solicited some help from Hugo of True RC Canada to see if he can shed some light on this subject.

    Each leg is equal in length and roughly square. Pitch angle is 25 degrees for this prototype. build like you would a cloverleaf or skew wheel. It works with 5 or 6 elements.

    Let the development begin

    -Alex
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by IBCrazy; 28th September 2014 at 10:10 PM.
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  2. #2
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    oooh... i got some scrap material around... gotta mes with one,
    after I figure out a better system for my RC truck

  3. #3
    Engineer for Jesus Christ IBCrazy's Avatar
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    I have put this on the backburner for a while. I have too many projects on my plate at the moment, but development on this will continue soon.

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

    videoaerialsystems.com - Performance video piloting

  4. #4
    Engineer for Jesus Christ IBCrazy's Avatar
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    It works!

    My first attempts failed, but with a little work I was able to get this antenna working well. Calculations were surprisingly accurate this time.

    Now I am working on an antenna to pair with this. I'm playing with a concept that I tried 4 years ago and failed. I know a lot more now. I hope I can figure it out this time.

    Building this one is really easy. Use 4 equal lengths of wire bent at 90 degrees. You must balance the cable or it will resonate, though.

    Click image for larger version. 

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    Leg length is approximately that of the cloverleaf. Each leg is equal length and the angle between them is 90 degrees for this prototype.

    More development will follow. There are likely considerably more gains to be made on this one.

    -Alex
    Last edited by IBCrazy; 27th September 2014 at 10:53 AM.
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  5. #5
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    hmmm... sounds like a weekend project

    BTW... your meter is a day ahead

  6. #6
    Fretsaw Jedi Roboforcer X2000's Avatar
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    I'm in, will build a set to try Alex, if you could spare a minute to answer some questions I'll love you more:
    1. Is it still at 25deg as stated in the first post?
    2. "Leg length = 3204/f in MHz." That's confusing me- divided 5800 (my frequency) from 3204 I'm getting 1.81. Is that the wire length in inches? I'm totally lost here how to calculate one blade wire length
    3. Are those are ferrite rings on yours in the second pic? If so, are they crucial, or just helps? Or are there only weights to prevent from resonating?
    4. In first post you mentioned 5-6 blades, but I see 4-5. The more the better, or what?
    5. You probably don't smoke anything "funny", so how you coming up with the names of antennas? (love them )
    If you're a noob, copy 1:1 what somebody already flies without too much questions, you'll find the answers later.
    PatrikE: I don't see anything wrong in your dump...
    Derrick:
    you are flying it LOS... You are doing it wrong.

  7. #7
    Engineer for Jesus Christ IBCrazy's Avatar
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    Tilt angle is 30-35 degrees. In this test unit, I accounted for the dielectric (plasti-dip and nylon at the feed) that I have not put on the antenna yet, so the test unit is hitting 1314MHz. I am guessing a shift of 30MHz once I finish it.

    The ferrite rings are a special type for microwave frequencies. They help me verify the true resonance of the antenna by taking cable resonance out of the equation. As you can see, I experimented with multiple rings to test the effect.

    This antenna ONLY works with 5 or 6 blades. It makes no difference whether you use 5 or 6. It will not work with 3 or 4.

    Leg length is approximately the same as a cloverleaf antenna on the same band.

    I came up with the name after building the model in my NEC engine. I am still optimizing this, mind you. This is a prototype. I have been able to get up to .85 axial ratio in simulation.

    -Alex
    Last edited by IBCrazy; 27th September 2014 at 10:49 AM.
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  8. #8
    Fretsaw Jedi Roboforcer X2000's Avatar
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    Thanks!
    If you're a noob, copy 1:1 what somebody already flies without too much questions, you'll find the answers later.
    PatrikE: I don't see anything wrong in your dump...
    Derrick:
    you are flying it LOS... You are doing it wrong.

  9. #9
    Engineer for Jesus Christ IBCrazy's Avatar
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    Just made something better

    I was reviewing current shifts and locations and stumbled upon a new idea and now I get this:

    Click image for larger version. 

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    Keeping this one under my hat for now. Already beats the original design by good margin on Axial ratio. I might pursue this one instead. The problem is that this one is going to be VERY hard to build.

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

    videoaerialsystems.com - Performance video piloting

  10. #10
    Engineer for Jesus Christ IBCrazy's Avatar
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    Doesn't work in 3 blade...

    This design will not work in 3 blade...

    -Alex
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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

    videoaerialsystems.com - Performance video piloting

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