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Spark RC controller antenna question
595 8 1-26 19:21
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bugalugs22
lvl.3
Flight distance : 61978 ft
Australia
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Hi there. Can someone let me know what the function on the left and right antenna is on the remote controller? I assume one is for video information and the other is for RC controls and other telemetry?

Is there any reference information on this I can refer to?
1-26 19:21
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DJI Tony
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Hi, thanks for the inquiry. We will check this information with our team for further clarification and to see if we could provide a reference for your query. Please let us know if you have other concerns. Thank you for your support.
1-27 15:12
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Lysak2003
Captain
Flight distance : 500052 ft
Ukraine
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Why do you ask?
1-28 12:22
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ssylca44
Captain
Flight distance : 115906 ft
Canada
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My guess, both antennae carry the same signal.
1-28 13:12
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Proteous
Second Officer
Flight distance : 182844 ft
Barbados
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the video is normally a separate antenna from the control or data stream antenna ,if your thinking high gain antennas you will need to change both
1-28 18:55
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Sparkz71
Second Officer
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Australia
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Technically, two antennas will create a directional pattern, focusing the RF signal forward & back between the 'antenna stack', unless you have a reflector behind the antenna to reflect the signal forward. That's why they say to face the antennas toward Spark. Compared to a single antenna, a 3db gain (double the signal) may be achieved in the required direction with two antennas.
A single antenna will be omni-directional, depending on the ground plane & wavelength, the focus of the RF signal will still be 360 degrees horizontally, but may be reduced vertically. (or vice-versa, based on orientation)   However a single co-linear antenna, depending on the number of phase elements, may achieve similar results, but will be physically longer - basically another way to stack antennas which will also focus the signal. Another option is the Yagi style antenna (also called a beam) - like a TV antenna.
Truckies used to have two CB antennas, one on each mirror. The signal would be strongest in front & behind the truck. No need for separate antennas for video/control if they are tuned within the bandwidth required. The main purpose is to create a directional signal, otherwise there would be no need to face the antennas 'forward' towards Spark as the signal would otherwise be 360 degrees.  Therefore, the antennas are 'stacked' & receiving the same info on each one.
Just remember, the higher the gain, the more directional the antenna will be. For example we can make a 12 db antenna, but it may have a 22 degree focus, or use a 6 db antenna & have a 45 degree focus. Imagine a torch/flash light with an adjustable reflector. Focusing the reflector will produce greater/brighter light in a smaller area, but travel further. Take away the reflector & light will spread in all directions, but not as bright.

Google "RF wifi antenna directional omni directional yagi stacked antenna" etc for references.
Example:
https://blog.solidsignal.com/tut ... acking-really-work/
https://www.allaboutcircuits.com ... nal-wi-fi-antennas/

As the third post said "Why do you ask?"
1-29 04:59
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Sparkz71
Second Officer
Flight distance : 24259 ft
Australia
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Proteous Posted at 1-28 18:55
the video is normally a separate antenna from the control or data stream antenna ,if your thinking high gain antennas you will need to change both

Terrestrial TV/Radio or Satellite may use a single antenna/dish for several frequencies at the same time. The antenna does not care. Each signal is basically AC (alternating current) and can be mixed together & separated at the other end. Think about network powerline adaptors.
Unless a different frequency out of tune from the antenna bandwidth (HF vs VHF vs UHF) is to be received, a single antenna can be used. The RC is 2.4 or 5 Ghz  so a single antenna can be used. 5 Ghz is close enough enough to half the wavelength or 2.4.  The 2.4 Ghz reception may be a full wavelength, whilst the 5 Ghz will be half a wavelength. Both will comply with a reasonable S.W.E.R .
1-29 05:14
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bugalugs22
lvl.3
Flight distance : 61978 ft
Australia
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Sparkz71 Posted at 1-29 05:14
Terrestrial TV/Radio or Satellite may use a single antenna/dish for several frequencies at the same time. The antenna does not care. Each signal is basically AC (alternating current) and can be mixed together & separated at the other end. Think about network powerline adaptors.
Unless a different frequency out of tune from the antenna bandwidth (HF vs VHF vs UHF) is to be received, a single antenna can be used. The RC is 2.4 or 5 Ghz  so a single antenna can be used. 5 Ghz is close enough enough to half the wavelength or 2.4.  The 2.4 Ghz reception may be a full wavelength, whilst the 5 Ghz will be half a wavelength. Both will comply with a reasonable S.W.E.R .

>Why do you ask

Firstly just to see if @DJI Tony will respond with his offer to find out for me (no Just kidding Im sure hes working on it). The DJI guys do a great job here.
The real reason is just to learn more about the controller. I guess the more I know about the technology the less likley I am to part with my drone.. As you can see some people think the antennas are for uplink and downlink. But I think the correct answer is they both transmit the same signal.  
1-30 22:46
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Sparkz71
Second Officer
Flight distance : 24259 ft
Australia
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bugalugs22 Posted at 1-30 22:46
>Why do you ask

Firstly just to see if @DJI Tony will respond with his offer to find out for me  (no Just kidding Im sure hes working on it). The DJI guys do a great job here.

I didn't think too hard. Combining a 2.4 & 5 Ghz antenna (full wave vs half wave vs 1/4 etc) is simple.  
Next is harmonic interference.  Example - https://whatis.techtarget.com/definition/harmonic
The same signal may be received/crossed within 1/2 waves or 1/4 or 1/8 etc.
It's too technical to explain more. But for example, I have had many problems with the old TV - 210 Mhz TV caused interference with 105 Mhz FM radio, vice versa.   The solution is to install a filter & reduce the unwanted frequency. But, obviously this is not simple within the RC as the 'feed' is built into the RC.
How technical do you wish to learn?  
1-31 00:45
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