Parabolic range extenders. Do they really work?

[Alicatt]

Last night I got 100meters before I got a warning that the signal was poor, but I've always suffered from poor performance around my house, and lots of times I don't even get that far. If I move a couple of miles west from my house the problem is gone and I can fly to my heart is content... as long as I don't go east! I still think it is something to do with the radar at the local airbase, even my ham radio registers an S7 in noise, I'm so looking forward to getting back to Scotland next month and get away from the high noise environment I'm in here.
It is something I have wondered about if those reflectors would shield the transmitter a bit from the radio noise.

 

[John Locke]

I broke down and ordered a set of these from Amazon but I have to say that they have made absolutely no difference to the max range or signal quality of my P4 at all.
I started thinking about why and I seem to remember from school days that reflected signals can actually destructively interfere and work to reduce the effective signal or can cause patchy signal loss if the reflected signal is slightly or completely out of phase with the original signal. Could it be that this is what is happening and why some people just cant get them to work?

Do specific brands work?

Jay, you are posting in the P4P section of the forum, but you stated you have a P4. Do you really mean you have P4P? There are different recommendations for these two different craft. Let us know and we may be able to mitigate your range issue a little, but the primary problem is your UK location, which reduces the RC RF power, as well as the craft. The RF power is reduced to comply with your governments CE requirements. Please confirm which craft you have.

 

[Brojon]

The parabolic reflectors do work - *if* they are true parabolics.
The one I got for my P4P works - adds about 50% range with trees and houses and such.
A much better solution would be to make your own dual quad antenna. Seriously - if you can install a commercial "flat panel" you can build and install a dual quad. Google it.

 

[Northern Canadian]

Range extenders to me would mean putting the bird out of VL of sight. Not a good idea in my opinion. Also in Canada breaking the law.

 

[Brojon]

Of course it's an opinion how you see them as "range extenders".
You could think of them as "getting past interference and items that block signal".
In any case I'm quite sure that everyone here is aware of the legalities in their particular part of the world - no need to bring it up in every single thread.

 

[GrammatonxXXxCleric]

Yesterday, I spent over 8 minutes waiting for my baby to re-establish video feed while she was flying a 5 mile circuit. She was fine and I knew it having planned and closely examined her course. I'm gonna do it 5 more times as I fly a very long mission divided in 5 parts. It is over 20 miles in totality and will take over 5 separate batteries. Each time she will be all on her own for some of the areas. And for the record... I don't lift my pinkie when sipping my tea, because I don't drink tea......

(And yes, I was using "Range extenders" which reduced video loss 25% or so).

 

[GrammatonxXXxCleric]

Range extenders to me would mean putting the bird out of VL of sight. Not a good idea in my opinion. Also in Canada breaking the law.

(You will now be required to completely stop for each and every stop sign you encounter. And at every intersection if turning right you will need to stop completely, then look both ways before proceeding. We will be watching 'cause not stopping completely.. would be breaking the law...)

 

[len750]

They help but not even close to a flat panel like a maxxuav DB2, parabolics like flat panels focus all the signal forward so you have to make sure you are pointing directly to the craft, if not it will be worse. I used a pair when I got my P4 many moons ago and it did help somewhat, then I got a flat panel and it was a game changer.

Like this one? ItElite MaxxRange Antenna (Full Kit)

 

[drvrbobob]

What country are you in? EU rules reduce transmitter power vs. US rules. Have you rotated the controller antennas many times? It is possible the lead is damaged within the controller. Have you tried flying in a COMPLETELY different area with the same results? Are the controller antennas both parallel to each other and pointed towards drone? When flying, are you aware of any object (Buildings, trees) between you and the drone? 800 meters equals 2,624 feet. In a high EMF noise environment, this would not be unheard of. Add in blocking objects and there's the answer. Keep in mind that this system is a "line of sight" rule. If there is any blockage from the antenna on the controller directly to the drone there will be greatly reduced distance results. The fact that you used the term meters tells me that you might be under EU rules. You could move to the U.S.A. where we mount military style microwave transmitters on our controllers and ride horses, wear cowboy hats and carry AR-15's while flying. Just saying....

Were you spying on me?

 

[Erised]

Like this one? ItElite MaxxRange Antenna (Full Kit)

That's the bigger model but yes those panels work very very well can be boosted as a option.
If you are not in a congested signal area you will not need the boost as these can take you out as far as your battery can bring you back safely.

 

[GrammatonxXXxCleric]

Were you spying on me?

Laughs...

The agency does not "Spy"
We just... monitor and observe...

(Your back porch light has burnt out, replace it so we can ensure your safe step....)

 

[IIIDaemon]

I broke down and ordered a set of these from Amazon but I have to say that they have made absolutely no difference to the max range or signal quality of my P4 at all.
I started thinking about why and I seem to remember from school days that reflected signals can actually destructively interfere and work to reduce the effective signal or can cause patchy signal loss if the reflected signal is slightly or completely out of phase with the original signal. Could it be that this is what is happening and why some people just cant get them to work?

Do specific brands work?

.
...Well of course they do..
.

 

[HomeyJay]

The parabolic reflectors do work - *if* they are true parabolics.
The one I got for my P4P works - adds about 50% range with trees and houses and such.
A much better solution would be to make your own dual quad antenna. Seriously - if you can install a commercial "flat panel" you can build and install a dual quad. Google it.

How do you establish that they are ‘true parabolics’?

 

[Bob Stahl]

I broke down and ordered a set of these from Amazon but I have to say that they have made absolutely no difference to the max range or signal quality of my P4 at all.
I started thinking about why and I seem to remember from school days that reflected signals can actually destructively interfere and work to reduce the effective signal or can cause patchy signal loss if the reflected signal is slightly or completely out of phase with the original signal. Could it be that this is what is happening and why some people just cant get them to work?

Do specific brands work?

The issue with range isn't complicated, its physics. To double your range you need to increase the radio path capability by 12 dB. Many people think it's only 3 or 6 db, well Maxwell's equations will disagree with that. Radio path capability is a combination if effective radiated power and sensitivity (taking into account antenna gains of losses). So slapping on a reflector is going to help, a little. Buy in real range terms it's not going to make a noticeable difference. Even if you put s 100 watt amp on it's not worth a jot. You need reciprocity for comms range. That means the radio paths capability must be the same in both directions. So for and amp to achieve greater range you need one at both ends. Or you can communicate to the drone, its range back is not improved. Any change of antenna does have reciprocity, but unless you go to some form of expensive phased array you will not achieve much. 9 dB gain on a Colinear. Still not double the range. Even then the story does not end. A sensitive antenna is also sensitive to any interference. So if range was reduced because of interference at the base end, a better antenna will not reduce it. You could of course use phased array self tracking antennas, they go for about 35000 USD. It's just an issue that really is difficult to solve with no one really having a solution. My guess is that the comms already uses MEMO or some form of CODFM. This helps multipath, but not interference signals. The comms are very good and better than some military equivalents. It's just very difficult to improve unless you do both the controller and the drone.

 

[GrammatonxXXxCleric]

Increasing the radiated TX power does not increase noise. It's the RX side that will introduce unwanted noise. Using either parabolics or better yet flat panel highly directional antennas minimizes the noise. I use RF-Linx amps with AGC (Auto gain control) along with Intelite flat panels. The amps have a whopping 20Db RX value but do very well to cut out the noise. The panels ensure it only listens to the direction it faces. Placing amps on the drone itself would be the capstone if the added weight didn't reduce fly time. It does work, and very well but the work needed and reduced fly time kinda dampens the effort. Lockheed and Raytheon make exellent high powered drones, but they usually run into the millions of dollars. (Searches E-bay for a deal on a used one)....

 

[HomeyJay]

Thanks both for the detailed comments but setting these aside for a moment, do you think that any form of destructive interference is possible between the reflected and directed signal?
I’m just trying to work out if any sight variation in anntenna positioning between different manufacturers could cause some reflectors to genuinely help while other brands don’t seem to do anything at all!

 

[GrammatonxXXxCleric]

Determining the focal length of a parabolic dish
Parabolic Dish Reflector
http://www.analyzemath.com/parabola/parabola_focus.html

The backing is also important. If the foil used is cheap and too thin, then it will have reduced reflecting power. Thick copper foil is the best.

The articles explain the position of the focal point. The position of the antenna in relation to the reflector is important

 

[N017RW]

Research ‘skin depth’ for the thickness required for reflectors at microwave frequencies.

It’s anout 1-10 micrometers. Thus material thickness is not an issue for even common household foils.

Also consider density as well. The perforated screen on your microwave oven is reflective @2.5 Gig yet is effectively transparent @visible.

 

[Harleydude]

I broke down and ordered a set of these from Amazon but I have to say that they have made absolutely no difference to the max range or signal quality of my P4 at all.
I started thinking about why and I seem to remember from school days that reflected signals can actually destructively interfere and work to reduce the effective signal or can cause patchy signal loss if the reflected signal is slightly or completely out of phase with the original signal. Could it be that this is what is happening and why some people just cant get them to work?

Do specific brands work?

I conducted many tests with my Inspire 1, and the results were pretty conclusive that I was getting 25% more range with the cheapo parabolic extenders. Here's a photo of the exact ones I have:

https://www.picclickimg.com/d/l400/...lic-Antenna-Range-Signal-Booster-Extender.jpg

 

[Jerry H]

Not trying to be rude here but flying 2 miles is asking for trouble. You guys must have very good eye sight. I get scared as soon as I lose visual sight of my drone. Guess I'm a coward lol.