Yagi-Uda Antenna Range Extender - Myth or Real Thing?

[AZDave]

I have the SG906 Pro and if you look closely at the RC "antennae" you'll see that there's no wires going to them...they're just dummies. The Yagi's won't work.

They probably don't work very well, but just because you don't understand HOW they work doesn't mean they are "dummies" and don't work at all. They couple to the existing drone antennas and shape the RF pattern after that. They don't need a wire or cable to do that, but a cable connection would be a lot more effective.

A Yagi antenna might have a dozen elements, but only one of them is normally dirven with transmitted energy. The rest of the elements receive energy from the driven element and change the phase by virtue of the elements in front being shorter and the one in back being longer, and then re-radiate that energy with the phase difference creating the shaped pattern. In the case of clip on Yagis, the driven element is still the original one in the drone and the clip on elements do the receiving/phase shift/re-radiating/pattern shaping. The energy coupling just isn't as effective.

 

[Gbeckwith]

They probably don't work very well, but just because you don't understand HOW they work doesn't mean they are "dummies" and don't work at all. They couple to the existing drone antennas and shape the RF pattern after that. They don't need a wire or cable to do that, but a cable connection would be a lot more effective.

A Yagi antenna might have a dozen elements, but only one of them is normally dirven with transmitted energy. The rest of the elements receive energy from the driven element and change the phase by virtue of the elements in front being shorter and the one in back being longer, and then re-radiate that energy with the phase difference creating the shaped pattern. In the case of clip on Yagis, the driven element is still the original one in the drone and the clip on elements do the receiving/phase shift/re-radiating/pattern shaping. The energy coupling just isn't as effective.

These Yagi wave shapers need RF in order to inductively excite the primary element. If RF is not there it will not work. I have had the SG906 apart and I can assure you that there is nothing in those antenna thingys except air.

 

[AZDave]

These Yagi wave shapers need RF in order to inductively excite the primary element. If RF is not there it will not work. I have had the SG906 apart and I can assure you that there is nothing in those antenna thingys except air.

The drone's regular antennas supply the RF and are the driven elements. The clip on Yagi elements are the rest of the antenna except for the driven element. Did you even bother to look up how a Yagi works? Try this:

Understand Yagi Antenna Theory: the Basics » Electronics Notes

Understand the basics of Yagi antenna theory: how does a Yagi antenna work: & the way the different elements react together.

www.electronics-notes.com

The only problem with the clip on Yagis is that the mutual coupling between the driven drone elements and the clip on parasitic elements isn't ideal because of spacing and intervening plastic.

If that explanation doesn't do the job for you I don't think anything will.

 

[Gbeckwith]

The drone's regular antennas supply the RF and are the driven elements. The clip on Yagi elements are the rest of the antenna except for the driven element. Did you even bother to look up how a Yagi works? Try this:

Understand Yagi Antenna Theory: the Basics » Electronics Notes

Understand the basics of Yagi antenna theory: how does a Yagi antenna work: & the way the different elements react together.

www.electronics-notes.com

The only problem with the clip on Yagis is that the mutual coupling between the driven drone elements and the clip on parasitic elements isn't ideal because of spacing and intervening plastic.

If that explanation doesn't do the job for you I don't think anything will.

I have been involved in electronics and RF wave propogation since the days of vacuum tubes and transistors including US Navy hf communications and weapons systems radars so I am quite familiar with yagi uda. I am not saying these little devices don't work. They actually work quite nicely for what they do on controllers where the antenna are external to the rc control box and the rf energy can be coupled to the yagi main element. What I AM saying is that the RG906 the antenna is internal and the low power of the transmitter and distance of the yagi from the internal transmitter antenna physically prevents the coupling required when mounted on those dummy elements. Please refer to: Do Drone Range Extenders Really Work Yes at Drone Valley on YouTube.

 

[AZDave]

I have been involved in electronics and RF wave propogation since the days of vacuum tubes and transistors including US Navy hf communications and weapons systems radars so I am quite familiar with yagi uda. I am not saying these little devices don't work. They actually work quite nicely for what they do on controllers where the antenna are external to the rc control box and the rf energy can be coupled to the yagi main element. What I AM saying is that the RG906 the antenna is internal and the low power of the transmitter and distance of the yagi from the internal transmitter antenna physically prevents the coupling required when mounted on those dummy elements. Please refer to: Do Drone Range Extenders Really Work Yes at Drone Valley on YouTube.

Ahh ... OK. I thought you were talking about clip on Yagis in general. My mistake, and I apologize.

I'm a degreed Electrical Engineer with two specializations ... circuit design and electromagnetic wave theory. I've also been a ham radio operator for over 50 years, with a background in antenna modeling and construction. Let's say were even on the technical background.

 

[Gbeckwith]

No worries, Dave. I used to love antenna theory and experimentation with long lines. Never got it down because I wasn't an engineer. Just curious and like to learn things. Cheers, Bro!

 

[Mid-AtlanticDroneServices]

Not sure how an extended range of flight fits in with the VLOS LAW in America.

First of all, it’s not a “law.” It’s an FAA *rule.* Secondly, I can see my drone at half a mile or more, particularly at night with no extra lighting. Third, in higher interference areas, “range extending” might mean adding 100m when flying near obstacles. That doesn’t mean all solutions work, of course.

 

[winters3dvr]

I always feel that Yagi antenna not only doesn't help but makes negative effect on a flying distance of my drones.
I have two 5.8GHz drones - SG906 Pro and Zino Mini Pro.
I bought from AliExpress 5.8 Yagi antenna extender. And what I see on both drones mounting Yagi makes negative effect.

Is it only me or 'The king is naked' ?

In both cases I've made RTH after losing signal.
With Yagi - about 3905 meters.

View attachment 136350


Without Yagi - about 5773 meters


View attachment 136351


BTW, Is anybody made declared 12 km (or near it) on Mavic Air 2S ?

I made it to 30,000ft. Only had to return because my battery was at 50% and wind was picking up.

 

[ElRubio]

First of all, it’s not a “law.” It’s an FAA *rule.* Secondly, I can see my drone at half a mile or more, particularly at night with no extra lighting. Third, in higher interference areas, “range extending” might mean adding 100m when flying near obstacles. That doesn’t mean all solutions work, of course.

The fact that it is an FAA “rule” may make it worse for those breaking the rule. I am a relatively new drone owner and not very familiar with FAA, but I work with the FCC regularly including enforcement. Their rules allow them to do warrantless searches and administer fines. I would suspect the FAA rules are similar.

 

[Mid-AtlanticDroneServices]

The fact that it is an FAA “rule” may make it worse for those breaking the rule. I am a relatively new drone owner and not very familiar with FAA, but I work with the FCC regularly including enforcement. Their rules allow them to do warrantless searches and administer fines. I would suspect the FAA rules are similar.

Well look, I'm fairly new to the hobby but I've been gathering knowledge quickly. My biggest realization is that the DJI Fly app is worthless when it comes to restricted zones. Given that makes me unlock an airport zone through geofencing, I was surprised to learning that marked TFR's weren't the same. So now, I use the B4UFLY app as well.

Concerning VLOS, the rule is the rule. I imagine the FAA can administer penalties. Were there damages or ill intent, criminal charges are possible. I'm not advocating flying BVLOS, just making the point that range extenders aren't just about going long distances. Some can improve signal at even shorter distances. For example, yesterday I was flying in the farmland area behind my house. There is a line of trees as a border, then various trees and obstacles around the field. I was investigating with the drone at low altitude in P mode. The signal dropped a bit when going around some of those obstacles. If a Yagi or Parabolic antennae cam help with that, it's worth it. The same applies if I'm 2,500 ft out at dusk. I have clear VLOS, but signal depends on a variety of factors.

 

[ElRubio]

Well look, I'm fairly new to the hobby but I've been gathering knowledge quickly. My biggest realization is that the DJI Fly app is worthless when it comes to restricted zones. Given that makes me unlock an airport zone through geofencing, I was surprised to learning that marked TFR's weren't the same. So now, I use the B4UFLY app as well.

Concerning VLOS, the rule is the rule. I imagine the FAA can administer penalties. Were there damages or ill intent, criminal charges are possible. I'm not advocating flying BVLOS, just making the point that range extenders aren't just about going long distances. Some can improve signal at even shorter distances. For example, yesterday I was flying in the farmland area behind my house. There is a line of trees as a border, then various trees and obstacles around the field. I was investigating with the drone at low altitude in P mode. The signal dropped a bit when going around some of those obstacles. If a Yagi or Parabolic antennae cam help with that, it's worth it. The same applies if I'm 2,500 ft out at dusk. I have clear VLOS, but signal depends on a variety of factors.

I had gotten the impression that you were making the distinction between FAA rule and law and that the rule is not as binding. I completely agree on using antennas to improve performance.

 

[Mid-AtlanticDroneServices]

I had gotten the impression that you were making the distinction between FAA rule and law and that the rule is not as binding. I completely agree on using antennas to improve performance.

Well, we’re not too far off. There is a distinction but then we get into the weeds of intent, the severity of the violation, etc. It becomes semantics. When we say “it’s against the law to fly this way” that’s not always accurate. But it is against regulations in many cases and that comes with various consequences.

 

[Jeanb]

Might want to ensure the controller is set to use ONLY the 5.8GHz bands then. See if that makes a with-without difference.

5.8ghz is not allowed in Israel so yagi 5.8ghz would not be effective

 

[albertly]

5.8ghz is not allowed in Israel so yagi 5.8ghz would not be effective

Actually, it is allowed
5.8GHz in Israel allowed since Apr 2021
פקודת הטלגרף האלחוטי [נוסח חדש], התשל"ב - 1972 - (Official Document in Hebrew)

Israel’s Ministry of Communications Opens the Floodgates to 5.8GHz-based Drones, Adv. Naama Margolis - Shibolet & Co. Law Firm

In recent years, Israeli drone operators and manufacturers have voiced mounting frustration over Israel’s sweeping prohibition on the use of civilian

www.shibolet.com

 

[Jeanb]

Actually, it is allowed
5.8GHz in Israel allowed since Apr 2021
פקודת הטלגרף האלחוטי [נוסח חדש], התשל"ב - 1972 - (Official Document in Hebrew)

Israel’s Ministry of Communications Opens the Floodgates to 5.8GHz-based Drones, Adv. Naama Margolis - Shibolet & Co. Law Firm

In recent years, Israeli drone operators and manufacturers have voiced mounting frustration over Israel’s sweeping prohibition on the use of civilian

www.shibolet.com

I have sent the document to DJI months ago and they said they are going to check. DJI did not yet open the 5.8ghz band in Israel, you have to use a moded app like Fcc mod to get it

 

[albertly]

They probably don't work very well, but just because you don't understand HOW they work doesn't mean they are "dummies" and don't work at all. They couple to the existing drone antennas and shape the RF pattern after that. They don't need a wire or cable to do that, but a cable connection would be a lot more effective.

A Yagi antenna might have a dozen elements, but only one of them is normally dirven with transmitted energy. The rest of the elements receive energy from the driven element and change the phase by virtue of the elements in front being shorter and the one in back being longer, and then re-radiate that energy with the phase difference creating the shaped pattern. In the case of clip on Yagis, the driven element is still the original one in the drone and the clip on elements do the receiving/phase shift/re-radiating/pattern shaping. The energy coupling just isn't as effective.

I personally don't have any beef with Yagi antenna.
But when it is proper Yagi antenna

TBS 2.4GHZ YAGI (11DB)​

But this one...



Maybe "a cable connection" is crucial.
BTW, I haven't seen any official recommendation for such an "Enhanced Signal Amplifier Clip".
I haven't seen it in FPV world, as well.

P.S.
And yes, you are correct - RF antenna is a "rocket science"
Brief tutorial on FPV antennas : The Best 5.8GHz Antenna for FPV Drone - Oscar Liang

 

[Mr500CM]

With line of site I was able to pull off a 2.37mile trip without loosing signal. The Yagi worked well but didn't do much when I flew out of site.

 

[AZDave]

With line of site I was able to pull off a 2.37mile trip without loosing signal. The Yagi worked well but didn't do much when I flew out of site.

Keep in mind that microwaves are essentially line-of sight themselves. You can get beneficial reflections and refractions off or around objects and terrain (also non-beneficial ones), but for the most part it's best to think of the control signal as a beam of light. Additional power might give a small advantage, but the loss in signal if it wraps around a hill or building is far greater than the normal distance-squared function. In such cases energy turns to heat far more quickly than it gets dispersed by distance alone.

 

[Sledman]

Not sure how an extended range of flight fits in with the VLOS LAW in America.

It fits well where I live....lots of interference.......

Not sure how an extended range of flight fits in with the VLOS LAW in America.

 

[Frank Dracman]

Of course a true YAGI antenna works. It's simple physics. The problem is they are HIGHLY directional. This is why you see 2 sides of the argument. People who understand how to use the YAGI have positive results those who don't end up with less range than the factory antenna since it's significantly less directional.