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DJI RC External Antennas

fadetoblack72

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Quite the contrary! DJI delivers the best stock range of any drone, without any necessary mods. They don't place any arbitrary limits. The physics of your problems are uniquely yours! If you really think you can out-engineer DJI's 10,000 engineers, best of luck to you! DJI's designs work well for 99.99% of uses. Flying for miles from behind and below groves of tall trees “with leaves" is a problem of your own making, and not any defect in DJI's antenna design.
Dji has 10000 engineers?
 

CactusJackSlade

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Trees with leaves.

Trees with leaves.

"No RC antenna or antenna mod can penetrate solid objects at any range."

Not really, it depends on frequency and received power. For example, you would likely be pretty unhappy if your cell phone stopped working because you walked behind a tree. The 2.4GHz channels (not far from cell bands 1, 10 and 23) will tend to pass through foliage better than the 5GHz but 5GHz has far less interference. Wet leaves are worse.

The power is not total power sent but power received, at both ends. Power received is dependent on the transmitted power; how well concentrated that transmitted power field is at the receiver; and how much of that power the receiver can gather. The FCC limits the transmitted power and is difficult to change anyway; a transmitter directional antenna will concentrate the power at the receiver; a bigger receiver antenna will gather more incoming power.

The one under discussion is the controller antenna. I have ordered a pair of Alfa APA-M25 dual band antennae, a well regarded directional antenna with a beam width of 60 degrees and beam height of 16 degrees; and a pair of 5" dual band omni antennae. Both (in theory) should perform better than the OEM antenna but might be somewhat more difficult to keep point correctly. Hard to know without a radiation plot for the OEM antenna. 3rd party dual band antennae also tend to be a mixed bag in terms of quality.

I expect the omni to gather more incoming signal and maybe improve the video range more; I expect the Alfa to do a better job at improving the signal the drone receives and maybe improve control range more. I also might experiment with mixing the antennae but I really don't know if there is some kind of MIMO or beaming forming in the receiver that would suffer from mis-matching the antennae.
If you want more penetration 900Mhz does better. The new Autel Evo 3 pro is triple band downlink. It sounds interesting.
 
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BroomRider

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If you want more penetration 900Mhz does better. The new Autel Evo 3 pro is triple band downlink. It sounds interesting.
I agree with the lower frequency being better for distance & obstruction resistance, but it's also slower for data transmission rates as I understand; if I'm incorrect, please let me know.

The USN use/used ELF (extremely low frequency) for communications with their submerged (ballistic missile) submarines, even on the other side of the world. Those frequencies can even penetrate the Earth's crust to transmit signals, albeit at a glacially-slow rate.

Most cordless phones (I mean, household telephones connected to a landline, not cellphones) use either the same 2.4 or 5.8GHz band as most drones. Although, the range is very short in comparison to some cordless phones in the past which used to use the 900MHz band. I still have 1 of those type cordless phones, which uses the 900MHz band & DSS which gives me a good connection even at 5-6 blocks distance in a suburban environment.

I expect a similar relationship with radio frequencies for drones in the higher bands. With all the data flow between the drone & the controller, I suspect the higher frequencies are needed.
 

CactusJackSlade

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I agree with the lower frequency being better for distance & obstruction resistance, but it's also slower for data transmission rates as I understand; if I'm incorrect, please let me know.

The USN use/used ELF (extremely low frequency) for communications with their submerged (ballistic missile) submarines, even on the other side of the world. Those frequencies can even penetrate the Earth's crust to transmit signals, albeit at a glacially-slow rate.

Most cordless phones (I mean, household telephones connected to a landline, not cellphones) use either the same 2.4 or 5.8GHz band as most drones. Although, the range is very short in comparison to some cordless phones in the past which used to use the 900MHz band. I still have 1 of those type cordless phones, which uses the 900MHz band & DSS which gives me a good connection even at 5-6 blocks distance in a suburban environment.

I expect a similar relationship with radio frequencies for drones in the higher bands. With all the data flow between the drone & the controller, I suspect the higher frequencies are needed.
Since I don't currently own an Autel with the triple hop frequencies, I don't know how well it works, but it would be sensible to think that 900mhz would give great penetration and distance, but maybe not the HD downlink clarity we are used to? Back in the "old days" if you wanted distance you went 900 Mhz... of course the downlink was standard def and only "good enough" back then. The new Autel drone will be interesting to watch the reviews...
 
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RSD1982

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I’d rather buy from another drone company that cares for his customers. We really need another competitor in the market to really challenge the price and practices of dji
It seems logical that a more expensive product performs better. It's a simple business model. Has been for years. Take a £15,000 car against a £100,000 car. You wouldn't suggest the manufacturer should make the performance the same in both models would you?
 

cdm3pro

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Trees with leaves.

Trees with leaves.

"No RC antenna or antenna mod can penetrate solid objects at any range."

Not really, it depends on frequency and received power. For example, you would likely be pretty unhappy if your cell phone stopped working because you walked behind a tree. The 2.4GHz channels (not far from cell bands 1, 10 and 23) will tend to pass through foliage better than the 5GHz but 5GHz has far less interference. Wet leaves are worse.

The power is not total power sent but power received, at both ends. Power received is dependent on the transmitted power; how well concentrated that transmitted power field is at the receiver; and how much of that power the receiver can gather. The FCC limits the transmitted power and is difficult to change anyway; a transmitter directional antenna will concentrate the power at the receiver; a bigger receiver antenna will gather more incoming power.

The one under discussion is the controller antenna. I have ordered a pair of Alfa APA-M25 dual band antennae, a well regarded directional antenna with a beam width of 60 degrees and beam height of 16 degrees; and a pair of 5" dual band omni antennae. Both (in theory) should perform better than the OEM antenna but might be somewhat more difficult to keep point correctly. Hard to know without a radiation plot for the OEM antenna. 3rd party dual band antennae also tend to be a mixed bag in terms of quality.

I expect the omni to gather more incoming signal and maybe improve the video range more; I expect the Alfa to do a better job at improving the signal the drone receives and maybe improve control range more. I also might experiment with mixing the antennae but I really don't know if there is some kind of MIMO or beaming forming in the receiver that would suffer from mis-matching the antennae.
all, just remember the basics. The power output is fixed. antennae can give you more "gain" by focusing the power into a narrower beam - longer range if pointed right at the bird. Or broader coverage (Omni directional) but the same power is spread over a wider area, so the range wont be any better. the exception would be if the antenna in the system is not well designed or has poor efficiency, then a better antenna can help IF well matched to the transmitter circuit.
 
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tlyons

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all, just remember the basics. The power output is fixed. antennae can give you more "gain" by focusing the power into a narrower beam - longer range if pointed right at the bird. Or broader coverage (Omni directional) but the same power is spread over a wider area, so the range wont be any better. the exception would be if the antenna in the system is not well designed or has poor efficiency, then a better antenna can help IF well matched to the transmitter circuit.
The "narrower" is in 2 dimensions. Longer omni antennae will have longer range by narrowing the beam vertically. Since (theorectically) straight up will be <400 ft away that's an easy compromise.
 

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