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Thread: MYTHBUSTERS: Letís talk seriously about antennas, or 10 myths busted.

  1. #21
    flying pirates ELLIOT's Avatar
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    really interesting! thnx sircana!
    pirates in the air, gentlemen on the ground
    (almost...)

  2. #22
    Australia's Home of FPV Mongrel Gear's Avatar
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    Thanks Sircana,

    A great help for laymen like me that can find all of this antenna stuff hard to understand.

    Cheers
    MG.
    Mongrel Gear Australia
    TBS Distributor - Down Under.
    Http://www.mongrelgear.com.au
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  3. #23
    Co-Pilot FPVdude's Avatar
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    Awesome! the wire demonstration is so cool! thanks, I learned a lot!

  4. #24
    unplugged
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    Thank You for the further antenna education

  5. #25
    I Like Waffles... SENTRY's Avatar
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    First off - GREAT thread!!!

    Quote Originally Posted by sircana View Post
    FALSE (WELL, EXCEPT IF YOU FLY LIKE A GIRL...). For omnidirectional passive antennas, there is only one way to increase the gain: flattening the radiation pattern. This means that when pushing the range limits you will lose signal every time you bank, climb or dive the plane. Useless IMHO.

    I prefer to design omni antennas with the lowest possible gain, and increase the gain in the receiver end. This way you can fly much more acrobatic without video glitches (except if you point the radiation null directly to the receiver, what is quite difficult to achieve in normal flight).

    I disagree with this one in some parts. And I add - I RESPECTFULLY disagree.

    I was warned by a few VERY visible pilot/engineers (who shall remain nameless) not to try 5dBi on the vTx. Bc I am hardheaded and don't have any kool lab tools, there was one way to learn the effects of higher gain on the vTx on my own... I did it. I set my personal range record with it (22 miles) with the same gain on the ground that shut me down a few miles closer to home. Now - in your defense, all of my "range records" are "flown like a girl" - gentle climb out, chop throttle at the distant end and glide home. The link I had 22 miles out I would have gladly done a victory roll - although that would have been disrespectful since I don't use nor intend to you an auto-pilot. That roll could have also been the end of my flight - so of course I played it like a pro and kept it simple.

    I'd guess that the 5/6dBi antenna DOES flatten the radiation pattern compared to my stock whip - but my course-corrections were uneventful, although I wouldn't call them "severe" banks, they were a neccessary evil to stay on course. The "oh shit you will see nasty dropouts" PMs I got just never happened in the real world.

    * note * I do lean my vTx antenna forward to compensate for the climb-out attitude of the rig. However, I have no lab data to quantify it's effectiveness. I also do not intend on putting another rig that far out just to get the real-world data that I try to gather in my FPV travels. My FPV needs have changed a lot ... the guys who are 5 miles out are 3.5 miles further out than I really ever intend to go these days.
    Last edited by SENTRY; 29th August 2012 at 10:35 PM.
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  6. #26
    Reckless Video Operator squishy's Avatar
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    This has got to be one of the best threads I have ever read here, thank you for taking the time to write it.
    Flight Club - "In thrust we trust"

  7. #27
    KB3WHA kenkos68's Avatar
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    It would be interesting to see the actual radiation patterns from the chamber for the other antennas; OMM's pinwheel @ 1.28 Ghz, home built clovers and sp's, VAS clovers and sp's, TrueRc's fans, etc.

  8. #28
    Navigator Kondor-FPV's Avatar
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    Last edited by Kondor-FPV; 30th August 2012 at 06:50 AM.
    www.fpvlr.com - Home of your favourite Custom FPV antennas.

  9. #29
    FPV Addict Scotttu's Avatar
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    Definitely a good thread.

    During my first four years we played with a variety of antenna's (Spinning) - for directional use in DF'ing bad guys signals.
    learned a lot about specific antenna's and radiation patterns but this is a step above that, by far!
    "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

    KF7TRX

  10. #30
    Quote Originally Posted by SENTRY View Post
    I disagree with this one in some parts. And I add - I RESPECTFULLY disagree.

    I was warned by a few VERY visible pilot/engineers (who shall remain nameless) not to try 5dBi on the vTx. Bc I am hardheaded and don't have any kool lab tools, there was one way to learn the effects of higher gain on the vTx on my own... I did it. I set my personal range record with it (22 miles) with the same gain on the ground that shut me down a few miles closer to home. Now - in your defense, all of my "range records" are "flown like a girl" - gentle climb out, chop throttle at the distant end and glide home. The link I had 22 miles out I would have gladly done a victory roll - although that would have been disrespectful since I don't use nor intend to you an auto-pilot. That roll could have also been the end of my flight - so of course I played it like a pro and kept it simple.

    I'd guess that the 5/6dBi antenna DOES flatten the radiation pattern compared to my stock whip - but my course-corrections were uneventful, although I wouldn't call them "severe" banks, they were a neccessary evil to stay on course. The "oh shit you will see nasty dropouts" PMs I got just never happened in the real world.

    * note * I do lean my vTx antenna forward to compensate for the climb-out attitude of the rig. However, I have no lab data to quantify it's effectiveness. I also do not intend on putting another rig that far out just to get the real-world data that I try to gather in my FPV travels. My FPV needs have changed a lot ... the guys who are 5 miles out are 3.5 miles further out than I really ever intend to go these days.
    Quote Originally Posted by sircana View Post
    6. IT IS DIFFICULT TO PUSH VIDEO RANGE LIMITS

    FALSE. Just buy a linear polarized omni antenna on the plane with high gain (let's say 6-8dB), fly flat, buy the bigger dish you can find, and keep it perfectly pointed to the plane. Easy.
    Yep, I know I am little bit contradicting myself... It is just that IMHO FPV must be an immersive experience. I don't want any glitch or pixel of noise reminding me that I am relying on a weak wireless link, and I want to concentrate in enjoying the experience, not in thinking about the way I need to fly to avoid signal losses.

    As you, nowadays 5 Km is way too much range for me. If I want to fly further, I drive to a closer spot.

    But there is only one truth: YOU fly like a girl...

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