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Old Oct 22, 2010, 02:30 AM
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matyou's Avatar
Bay Area California
Joined Dec 2009
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Question
30 dBi Grid Antenna

Hi,

I have been wondering what it takes to create a FPV plane that will be able to reach extreme distances. One of the 3 major challenges is the video feed besides RC and battery capacity. So to achieve such distances can a 30 dBi grid antenna be used? I understand that the beam width is only 5.3 degrees but can a antenna tracker system accurately point the antenna at the plane such that the plane will be in the narrow rf window?

Thanks
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Old Oct 22, 2010, 02:32 AM
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chancesAU's Avatar
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Of course, also at over a mile, that small rf window opens up quite a bit.
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Old Oct 22, 2010, 07:12 AM
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Old Blighty
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5.3 degrees may well provide a wide window to fly in when you're miles out, but it's still only 5.3 degrees and means you'll have to keep your antenna locked on and pointing in exactly the right direction to a very high accuracy for the entire flight.

I'm not sure what the gain is on a normal satellite TV dish, but they're tricky enough to line up; just imagine how much harder it would be if the satellite were moving!

Antenna trackers are great (I use one), but the thing to note here is that although as a pilot you can cope with video degradation due to static or a weak signal, the antenna tracker which depends on a solid audio channel will not. That said, when you're miles out you should only need a successful data packet every 10, maybe even 30 seconds to keep it pointing on course.
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Last edited by Ian Davidson; Oct 22, 2010 at 07:17 AM.
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Old Oct 22, 2010, 07:19 AM
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trappy's Avatar
Austria
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in our experience the RF window doesn't open up considerably. moving the antenna 2 or 3 centimeters can be the difference between bad signal and perfect signal.

forget about using an antenna tracker for dish antennas far out, the antennas do not always need to be pointed at the plane to pick up the best signal
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Old Oct 22, 2010, 10:44 AM
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Amherst, VA
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30 dbi dish antennas are really meant for point to point, not to track a moving target. At 5.3 degrees of beam, there is little servo resolution to keep you on target. If you can increase the servo resolution (ie gear it down), then this would be better and make this a much better scenario.

Two dishes pointed 3-4 degrees apart on a diversity controller would work great.

-Alex
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Old Oct 22, 2010, 11:52 AM
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Last edited by matyou; Oct 22, 2010 at 12:58 PM.
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Old Nov 14, 2010, 11:49 AM
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Joined Sep 2010
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antenna

Quote:
Originally Posted by IBCrazy View Post
30 dbi dish antennas are really meant for point to point, not to track a moving target. At 5.3 degrees of beam, there is little servo resolution to keep you on target. If you can increase the servo resolution (ie gear it down), then this would be better and make this a much better scenario.

Two dishes pointed 3-4 degrees apart on a diversity controller would work great.

-Alex
24dbi hypergain dish antenna,, 8 degree beam and a 14 dbi flat panel with a duo reciever 2.4 ghz ive gotten 2 miles out and 2200 ft up . today im gunna test the antenna traker on the flat patch and see how the 2 work together .. i dont trust the antenna tracker ..
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Old Nov 14, 2010, 10:32 PM
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tested it

well it worked great.. forgot to set home on the tracker.. but once i did that it freaking got it.. couldnt wait till the fog went .. flew only depending on my gps and the hope my antenna worked then i got a break




THIS IS WHY.wmv (14 min 17 sec)



i went 5 miles out batt was so low i lost it
but that vid is processing
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