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Old Aug 07, 2012, 01:40 PM
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Romania, Dolj, Craiova
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If you consider the flights with "the other" system are relevant, there are some 16 km flights with 600mW IRC transmitter and not remember what receiver.
The antenna setup is identical with the 18km flight: CL and 9 turn helix.
Given the fact that the 5dB receivers sensitivity difference equates the 3x difference of transmitters power, I think these flights are almost perfect match and this 15-20km ballpark is the maximum that can be obtained with such equipment.
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Old Aug 07, 2012, 02:01 PM
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Originally Posted by RENATOA View Post
If you consider the flights with "the other" system are relevant, there are some 16 km flights with 600mW IRC transmitter and not remember what receiver.
The antenna setup is identical with the 18km flight: CL and 9 turn helix.
Given the fact that the 5dB receivers sensitivity difference equates the 3x difference of transmitters power, I think these flights are almost perfect match and this 15-20km ballpark is the maximum that can be obtained with such equipment.
That's why I will try to make different equipment to challange that
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Old Aug 07, 2012, 03:47 PM
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How about a short helical on the VTx mounted on a 180 servo.
Fly out with VTx helical pointing to home, slow turn and rotate servo to point at home, until turned 180 for home, straight line flight back -- do-able...maybe?
Maybe use the onboard GPS to always point the VTx antenna at home, are you any good at Arduino programming? do-able?

Nigel.
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Old Aug 08, 2012, 03:25 AM
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The antenna coax is too rigid, need to pan the whole VTx.

Given the three grams weight of these 200mW VTxes, I would rather mount two, each with its own 3 turn helix, one pointing back, and one ahead, for return. The switching operates the VTx power using the radio and/or RTH logic.
Such helix more than doubles the range and ensure about 60 degrees coverage, so only the direction changes in an angle more than 30 degrees will be not covered with image, i.e. when the plane fly on a circle around you, with one of the wings pointing to home.
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Old Aug 08, 2012, 06:03 AM
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Making a more than 8-10 turn helical is useless. The next setup for 5,8 ghz wich i will try with futurebreeze will be a 4-6 turn helical with parabolic dish
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Old Aug 08, 2012, 06:16 AM
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10km can be done with an 8 turn.

I have heard the dish idea works very well. love to see what you come up with.

right now I am testing Hugeone new antenna. I need to compile the first few videos to show how that is working. no range yet as the weather is hot and humid. I am waiting for a sunny dry day.
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Old Aug 08, 2012, 12:48 PM
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Originally Posted by costi_n View Post
Making a more than 8-10 turn helical is useless. The next setup for 5,8 ghz wich i will try with futurebreeze will be a 4-6 turn helical with parabolic dish

Yes I have made the dish too, 30cm diameter for 22dbi...
you can do a backfire helix too to feed the dish...
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Old Aug 08, 2012, 01:06 PM
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What angles of coverage are we talking for this plate ?
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Old Aug 09, 2012, 01:24 AM
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Originally Posted by renatoa View Post
what angles of coverage are we talking for this plate ?
6 :d
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Old Aug 09, 2012, 04:12 AM
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I've heard for long range 5.8Ghz linear directional is the best but I'll have to try the helical some day.
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Old Aug 09, 2012, 11:19 AM
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Originally Posted by FPVAustralia View Post
I've heard for long range 5.8Ghz linear directional is the best but I'll have to try the helical some day.
hardly the best..

I made a tuned vertical dipole and used a 5.8ghz 10-12dbi patch which I dismanteled and tuned to 5705, results were as you see in the video on 200mw, I'd say a 5km potential, maybe 10 with a higher gain whip on the model, you can see cross-polarization losses when I roll left or right (I do it on purpose in the video).
My area is not good for this frequency since there are hundreds of wind generators which use 5.8ghz wi-fi at high power to communicate with base and with each other.


5.8 ghz patch + dipole test (5 min 45 sec)



with a 32dbi grid or parabolic antenna the record is possible, but those parabolic antennas weigh like 20lbs... it sux to be stuck with such a mammoth antenna just to do a record.

It's nice to develop antennas that the fpv community can use and mount on a light duty antenna tracker.
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Old Aug 09, 2012, 05:43 PM
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Quote:
Originally Posted by RENATOA View Post
The antenna coax is too rigid, need to pan the whole VTx.

Given the three grams weight of these 200mW VTxes, I would rather mount two, each with its own 3 turn helix, one pointing back, and one ahead, for return. The switching operates the VTx power using the radio and/or RTH logic.
Such helix more than doubles the range and ensure about 60 degrees coverage, so only the direction changes in an angle more than 30 degrees will be not covered with image, i.e. when the plane fly on a circle around you, with one of the wings pointing to home.
With a different idea in mind, what would the ramifications be to run 2 x 5.8 vTx's on a plane at the same time, using common power?
I would think on different channels the two vTx's would swamp each other to some degree, but if both are on the same channel?
Or would you need some fancy lab equipment to ensure both vTx's were tuned in to the same exact channel?
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Old Aug 10, 2012, 01:01 AM
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Originally Posted by AussieHoppy View Post
With a different idea in mind, what would the ramifications be to run 2 x 5.8 vTx's on a plane at the same time, using common power?
I would think on different channels the two vTx's would swamp each other to some degree, but if both are on the same channel?
Or would you need some fancy lab equipment to ensure both vTx's were tuned in to the same exact channel?

I am not renato but I make professional antennas and can answer that the best way to do that would be with a LHCP on 5640 and a RHCP on 5945 , so using the furthest channels and different circular polarization, and have a LHCP and a RHCP helicals on the diversity receiver on those two different channels on the ground.

the two polarizations (left hand and right hand) will reject interference from each other.
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Old Aug 10, 2012, 01:18 AM
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Why consume double power, is not difficult to switch them ...
Even maintaining both transmitters live, they will transmit only along the fuselage, the lateral of the plane will not be covered anyway.
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Old Aug 10, 2012, 01:20 AM
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Originally Posted by RENATOA View Post
Why consume double power, is not difficult to switch them ...
Even maintaining both transmitters live, they will transmit only along the fuselage, the lateral of the plane will not be covered anyway.
in fact it would only be a record setup as you can turn around using RTH, than switch it off, after picture is back from the front aimed antenna.
But it's not practical, just a means to an end, far from what I am looking to do.
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