DJI RC External Antennas

[Siam]

At the end of the day, I have better distance by modding my controller. And I have found I have a more remarkable change if using quality antennas and not cheap no brand ones. Over two miles in an urban environment is pretty good. The stock controller antennas never gave me half of that on the same route.

Tests were done on multiple days on the same flight paths and at the same time.

I have worked in EW (Electronic Warfare) for most of my adult life. I know how signals work and reception works. Certain modulations work differently than others. Some modulations work well in multi-path environments, even with low power.

And yes, I don't care if you are in a triple-canopy jungle or in a city environment.........all things being equal: if the ERP is higher (in layman's terms-more power) then the signal has a better chance of reaching the receiver.

 

[Brojon]

Having used all the various drone RC antenna mods myself, I stand by my statement, as it pertains to RC antenna mods. The RC antenna mods are not designed to penetrate solid objects nor dense trees, and are not intended for close range, unlike home wifi. All large solid objects and large trees with heavy foliage that visually block for the LOS for more than 5 seconds will cause loss of signal. At least we agree that obstructing trees are problematic.

My question was also never answered by the person I asked it of, which would have proven my premise. Always maintain a clear LOS for best signal, with and without antenna mods.

Home wif-fi is 2.4 and 5.8 Ghz - same as DJI drones, thus share the same limitations.
Stuff like drywall, treated woods, brick walls do not attenuate signals to a great degree unless they have metal as part of their makeup.
We can agree that LOS is still the best guarantee for best signal in any case.

 

[GadgetGuy]

We can agree that LOS is still the best guarantee for best signal in any case.

That was my main point. To get the best signal and range out of any antenna mod, always maintain clear LOS, and also point the antennas at the drone. Same is true for the stock antennas, despite the omnidirectional claim.

 

[Brojon]

At the end of the day, I have better distance by modding my controller. And I have found I have a more remarkable change if using quality antennas and not cheap no brand ones. Over two miles in an urban environment is pretty good. The stock controller antennas never gave me half of that on the same route.

Tests were done on multiple days on the same flight paths and at the same time.

I have worked in EW (Electronic Warfare) for most of my adult life. I know how signals work and reception works. Certain modulations work differently than others. Some modulations work well in multi-path environments, even with low power.

And yes, I don't care if you are in a triple-canopy jungle or in a city environment.........all things being equal: if the ERP is higher (in layman's terms-more power) then the signal has a better chance of reaching the receiver.

If you know how signals work then you know about antennas and gain and power densities following the inverse square law. DJI remotes put out the max allowed by law - say 1 watts. To get a 3db increase in signal you'd need 4x the power - 4 watts. If you look at the power boosters used they are simply wifi signal amps rated at around 4 watts. That 4 watts improvement will net you a half again distance increase - not double. That's provided the impedance is a good match and the cable and connectors are top notch. Then that is usually one way unless they use dual amp modules (which they suck at receiving).
There are valid antenna designs that can give significant improvements and some of the passive panels might even use them. But they won't say what they use nor provide data to back it up.
Google Biquad or double-biquad antenna design if you want something that actually works.
At the end of the day you have to have precise antenna impedance matching and very short leads as excessive length and/or connectors can nix any actual gain.

Biquad Antenna Construction

 

[Siam]

If you know how signals work then you know about antennas and gain and power densities following the inverse square law. DJI remotes put out the max allowed by law - say 1 watts. To get a 3db increase in signal you'd need 4x the power - 4 watts. If you look at the power boosters used they are simply wifi signal amps rated at around 4 watts. That 4 watts improvement will net you a half again distance increase - not double. That's provided the impedance is a good match and the cable and connectors are top notch. Then that is usually one way unless they use dual amp modules (which they suck at receiving).
There are valid antenna designs that can give significant improvements and some of the passive panels might even use them. But they won't say what they use nor provide data to back it up.
Google Biquad or double-biquad antenna design if you want something that actually works.
At the end of the day you have to have precise antenna impedance matching and very short leads as excessive length and/or connectors can nix any actual gain.

Biquad Antenna Construction

Nice post but I guess I am confused on this part:

"Google Biquad or double-biquad antenna design if you want something that actually works."

What I did actually works so I was wondering what you were referring t

A key point in your post is that the impedance must be matched as close as possible. I think that is where people fail when experimenting and just buy any antenna and assume they are the same. They are not. Impedance mismatching causes reflected power and in turn, decreases performance. It will also in the long run potentially damage your transmitter because of the mismatch. You know this, but many people modifying things do not..

I noticed a big difference between using cheap antennas and ones that I used from a better manufacturer.

I have made my own antennas for my antenna farm (I am a Ham). Reflected power causes hosts of problems.

 

[Brojon]

Nice post but I guess I am confused on this part:

"Google Biquad or double-biquad antenna design if you want something that actually works."

I have made my own antennas for my antenna farm (I am a Ham). Reflected power causes hosts of problems.

Nifty - then you know why I have beef with the commercial "booster" vendors - no Smith charts, nothing.
Most will not tell me what they have for adjusting VSWR, nor a procedure to tune it.
Doesn't foster any confidence in their product at all.
The double Bi-Quad antennas are pretty much the sweet spot IMHO since they can provide 13 db gain, easy to make and NOT super directional. Far superior to most common antenna types.
The ones that really crack me up are the supposed yagi antennas you see people selling with equal-spaced, equal length dipoles along an axis.

 

[Siam]

Nifty - then you know why I have beef with the commercial "booster" vendors - no Smith charts, nothing.
Most will not tell me what they have for adjusting VSWR, nor a procedure to tune it.
Doesn't foster any confidence in their product at all.
The double Bi-Quad antennas are pretty much the sweet spot IMHO since they can provide 13 db gain, easy to make and NOT super directional. Far superior to most common antenna types.
The ones that really crack me up are the supposed yagi antennas you see people selling with equal-spaced, equal length dipoles along an axis.

To be honest..no one really buys a 2.4/5.8 antenna and would tune it. They expect it is tuned. Or should be LOL. It is not like VHY/UHF/HF where you do tune the antenna.

Yagi's are not equally spaced as you said. I do VHF/UHF Satcom comms as a Ham as well. The first antenna I made was from clothes hangers and PVC pipe (Yagi) It works just as well s a store-bought one

 

[tlyons]

To be honest..no one really buys a 2.4/5.8 antenna and would tune it. They expect it is tuned. Or should be LOL. It is not like VHY/UHF/HF where you do tune the antenna.

Yagi's are not equally spaced as you said. I do VHF/UHF Satcom comms as a Ham as well. The first antenna I made was from clothes hangers and PVC pipe (Yagi) It works just as well s a store-bought one

I am a high frequency engineer and as a hobby have designed a big wifi network, built several long range repeaters and generally Frankenstein most of my electronics. I really like the Alfa; nice compromise between cost and actual engineered products. Enjoy the Smith charts, VSWR plots, and irradiance diagrams.

Oh, and Apa M25 works really well for the Mini 3 Pro in both 2.4 and 5G bands. Easily 50% range increase in an urban area.

APA-M25-6E

WiFi 6E Indoor Directional Antenna Specifications Frequency 2.4 - 2.5 GHz 5.150 - 5.875 GHz 5.975 - 7.125 GHz V.S.W.R ≦ 2.5 Antenna radiation Directional Gian 8 dBi @ 2.4 – 2.5 GHz 10 dBi @ 5.150 – 5.875 GHz 9 dBi @ 5.975 – 7.125 GHz Polarization Linear, Vertical Vertical beamwidth 16 degrees...

www.alfa.com.tw

 

[Brojon]

I am a high frequency engineer and as a hobby have designed a big wifi network, built several long range repeaters and generally Frankenstein most of my electronics. I really like the Alfa; nice compromise between cost and actual engineered products. Enjoy the Smith charts, VSWR plots, and irradiance diagrams.

Oh, and Apa M25 works really well for the Mini 3 Pro in both 2.4 and 5G bands. Easily 50% range increase in an urban area.

APA-M25-6E

WiFi 6E Indoor Directional Antenna Specifications Frequency 2.4 - 2.5 GHz 5.150 - 5.875 GHz 5.975 - 7.125 GHz V.S.W.R ≦ 2.5 Antenna radiation Directional Gian 8 dBi @ 2.4 – 2.5 GHz 10 dBi @ 5.150 – 5.875 GHz 9 dBi @ 5.975 – 7.125 GHz Polarization Linear, Vertical Vertical beamwidth 16 degrees...

www.alfa.com.tw

That's all credible info including the modest 10 dbi gain claimed.
They don't mention line losses which can be a factor with these type cable/connectors. As long as they're kept short and tight shouldn't be an issue.
Too bad the drone antenna vendors can't be bothered to include the same kind info.
This thing is cheap enough I may buy two and try them on my venerable Mavic Pro.
Thanks! Good find!

 

[Brojon]

To be honest..no one really buys a 2.4/5.8 antenna and would tune it. They expect it is tuned. Or should be LOL. It is not like VHY/UHF/HF where you do tune the antenna.

The antennas that are meant to be just screwed on in place of an existing antenna are probably ok.
But drones are a bit different in that there are usually two antennas, and they usually require routing a longer cable to the new external antenna.
In reality all antennas require matching to a degree.
You can assume they are already GTG but you're also assuming risk and ignoring losses that may make it perform worse.
Microwaves can be incredibly sensitive to transmission line mismatches.
You buy an external antennas for even a CB radio and it'll tell you how to adjust the antenna.

 

[Siam]

The antennas that are meant to be just screwed on in place of an existing antenna are probably ok.
But drones are a bit different in that there are usually two antennas, and they usually require routing a longer cable to the new external antenna.
In reality all antennas require matching to a degree.
You can assume they are already GTG but you're also assuming risk and ignoring losses that may make it perform worse.
Microwaves can be incredibly sensitive to transmission line mismatches.
You buy an external antennas for even a CB radio and it'll tell you how to adjust the antenna.

I am not sure if you are agreeing with me or not LOL. My point was that it is normal to buy an antenna for the ranges we are talking about not really being able to easily be tuned. BTW: even if they were easily tuned, most people would not have the equipment and/or know how to do it.

I mentioned that buying a quality antenna from a reputable company in my experience performs better. Most likely because they are tuned correctly from the git-go.

Losses and impedance mismatch from the tranmission line is a concern. Again, most people on this forum probably have no idea how to tune an antenna or check it anyway.

Yada yada........smith charts and formalized testing are great. At the end of the day, external antennas perform better for me. And cheap antennas from Amazon do not perform as well as higher quality ones.

People that have CB's or if they are Hams will tune every antenna they have. Heck, in the starting days of radio they used a light bulb to help check SWR.

 

[Brojon]

I am not sure if you are agreeing with me or not LOL. My point was that it is normal to buy an antenna for the ranges we are talking about not really being able to easily be tuned. BTW: even if they were easily tuned, most people would not have the equipment and/or know how to do it.

I mentioned that buying a quality antenna from a reputable company in my experience performs better. Most likely because they are tuned correctly from the git-go.

Losses and impedance mismatch from the tranmission line is a concern. Again, most people on this forum probably have no idea how to tune an antenna or check it anyway.

Yada yada........smith charts and formalized testing are great. At the end of the day, external antennas perform better for me. And cheap antennas from Amazon do not perform as well as higher quality ones.

People that have CB's or if they are Hams will tune every antenna they have. Heck, in the starting days of radio they used a light bulb to help check SWR.

So... ignorance is bliss?
In the end what you are saying is you have an entirely subjective opinion.
That's cool - it's your money and your drones.
You talk about people not knowing how to test or tune their antennas but yet assert it's within their grasp to disassemble the controller, void their warranty and then assume everything goes well?
I'm more of the Missouri mentality - show me the facts.
But that's really enough of this particular conversation so let's drop it.

 

[tlyons]

That's all credible info including the modest 10 dbi gain claimed.
They don't mention line losses which can be a factor with these type cable/connectors. As long as they're kept short and tight shouldn't be an issue.
Too bad the drone antenna vendors can't be bothered to include the same kind info.
This thing is cheap enough I may buy two and try them on my venerable Mavic Pro.
Thanks! Good find!

I'll go one further; here's a cheap source I bought from and they were legit: DJI Mavic Mini kit RC Drone antenna upgrade RP-SMA kit by Alfa Network APA-M25 | eBay

At the risk of joining a thread hijack, tuning these small antennae that are both multi-band and wideband is a thankless business; one band at 2.4-2.5GHz and the highest at 5.725GHz to 5.875GHz. Hence 12.5cm - 5.1cm. What wavelength would you even tune them to?

At least inside the Alfa, the antenna is a PCB layout. To some extent, they are what they are. You *can* adjust with an Exacto knike to make them shorter but that's about it. Even then, they are complex shapes.

Here's a teardown and a VNA for the Alfa:

The VNA analysis is really the point; the Alfa folks have designed a lovely *3 band* antenna shown at 12:55. At about 18:00 or so he proceeds to ruin it.

Good luck!

 

[Siam]

So... ignorance is bliss?
In the end what you are saying is you have an entirely subjective opinion.
That's cool - it's your money and your drones.
You talk about people not knowing how to test or tune their antennas but yet assert it's within their grasp to disassemble the controller, void their warranty and then assume everything goes well?
I'm more of the Missouri mentality - show me the facts.
But that's really enough of this particular conversation so let's drop it.

Of course, it is subjective. It is based on observation and repeated testing. There are no scientific readings if that is what one needs to "prove" something works or not. The topic is about using external antennas and if they work. So far it appears that they do. Because I ( or others) have not tested this under strict scientific testing guidelines or engineering processes does not mean that it is invalid.

Look at the history of electronics. Lots of things happened by accident and experimetnation.

And yes, it is within most people's capabilities to take off 4 screws and unplug and plug in a new set of antennas LOL. That is a far cry from having knowledge of how to tune an antenna system. Changing antennas is a simple mechanical process that does not involve any electronic knowledge or theory.

I would hope that an educated person like yourself can see the difference.

And no one is telling anyone to do anything. The forum is to discuss ideas. One does something to their own property at their own risk.


Golly gee Anyway, good discussion.

 

[Brojon]

I'll go one further; here's a cheap source I bought from and they were legit: DJI Mavic Mini kit RC Drone antenna upgrade RP-SMA kit by Alfa Network APA-M25 | eBay

At the risk of joining a thread hijack, tuning these small antennae that are both multi-band and wideband is a thankless business; one band at 2.4-2.5GHz and the highest at 5.725GHz to 5.875GHz. Hence 12.5cm - 5.1cm. What wavelength would you even tune them to?

At least inside the Alfa, the antenna is a PCB layout. To some extent, they are what they are. You *can* adjust with an Exacto knike to make them shorter but that's about it. Even then, they are complex shapes.

Here's a teardown and a VNA for the Alfa:

The VNA analysis is really the point; the Alfa folks have designed a lovely *3 band* antenna shown at 12:55. At about 18:00 or so he proceeds to ruin it.

Good luck!

Thanks! That is pretty interesting.
The good news is that the drone bands are mostly even harmonics - so 2.4Ghz 1/4 wave = 5.8Ghz 1/2 wave.
Yes I know it's not perfect but it in fact works fairly well in the real world. I have an 2.8-5.8Ghz RF power meter that just uses a simple rubber ducky antenna with no fuss.
I had not considered using a circuit board for the dual Bi-Quad antenna but it should work.
I know at least one manufacturer offered a "planar" antenna and a couple of others picked up on that term.
If you've not tried a DBQ antennas you should give it a spin - moderately directional with decent gain, easy to make.

 

[BroomRider]

While I have interest in maximizing the communication efficiency between the RC controller & my M3P, I'll wait until it's out of warranty before I go performing any elective surgery on my RC controller.

Great discussion thread, though!

In my explorations on the topic, I found this, which might be useful.

 

[IcedieG]

Have any of these mods been affected by the latest update? or is there no way that these software updates would make any difference or hindrance at all on hardware mods?

 

[Siam]

Have any of these mods been affected by the latest update? or is there no way that these software updates would make any difference or hindrance at all on hardware mods?

I don't see how it could. I mean, it is just a difference in antennas.

 

[GadgetGuy]

Have any of these mods been affected by the latest update? or is there no way that these software updates would make any difference or hindrance at all on hardware mods?

If anything, any improvement in range on the latest FW would only be magnified by a better antenna.

 

[Eli123]

A YouTube showed up recently showing the removal of the two internal antennas on the DJI RC and installing external antennas. The purpose was to help with the range issues being reported on the Mini 3 Pro. Aside from voiding any warranties I feel this will improve the range regardless of any firmware updates that will also improve range. I imagine the antennas on this controller were put inside for appearances sake but for those who prefer function over form it seems to be a no-brainer. I suppose it is possible that these internal antennas may be of a special design the does in fact provide the same or greater level of performance as any external antennas but I would need to see the technical report and data before I believe it.

it's simple, ask for antenna data sheet, every 6dBm you add you double the range, i.e. if your original antennas gain are around 3dBi and you replace it with 9dBi directional antenna, you double the range