Extending the range


Kenjancef, thanks to you I just pulled the trigger on a couple of VERY expensive antennas. After doing some research I opted for the Air-Blade LHCP antennas that are 5 elements with 1.5db gain. They come as a pair for $68 shipped. Can be used for TX or RX. I'll pick up a panel antenna after my PayPal account recovers. ;)

Air_Blade.jpg
 
For the rx I use 11dbi panel antenna,for the tx is better to use 3 blade or 4 blade cloverleaf?Thanks.
 
Hey folks
Hope you all don't mind if I chime in here. I was a wireless systems integrator and engineer for many many years so I'd like to share a few simple guidelines you can use to get the best range from any RC system.

Polarization

One of the first rules is to keep the polarization the same between transmitting and receiving antenna(s). Typically that's vertical, horizontal, cross or circular. The flight control receiver antennas in the P2 are attached to the landing gear vertically so keeping your controller antenna vertical gives the best general signal. Having the TX antenna sideways is worse and pointing it at the aircraft is way worse (explained in next paragraph). Clover leaf antennas are popular for the P2 video transmitter and they're circularly polarized. About any antenna will receive this polarization closer in but to get good range you need the same polarization at the receiving end.

Also, the strongest signal is radiated 90 degrees off an antenna element so if your controller TX antenna is oriented vertically and your aircraft is located straight out from it 90 degrees, you're at the best TX/RX angle.

Line of Sight

One picture in an earlier post shows a nice panel antenna used to receive video that's mounted directly to the back of the control transmitter. That's great but it was also directly in front of the controller TX antenna, effectively blocking the signal forward to where the aircraft would be. 2.4Ghz and 5.8Ghz signals can be blocked, reflected and absorbed easily. Line of site is critical. That's why when at reception limits the video many times gets noisy when the drone is turned around for the return trip. The gimbal and camera block line of sight from the antenna to receiver. So any antenna must be positioned line of site to the target antenna to get maximum range.

Another earlier post showed an attempt at hanging the TX antenna way below the aircraft. Right idea but too aggressive. Higher frequencies don't travel through coax well and have a tendency to dissipate into the cable. Connectors also cause a small amount of VSWR (Voltage Standing Wave Ratio - or in other words a small of amount of TX energy is reflected back that effectively reduces the output to the antenna - too much VSWR will burn out the transmitter). The more connectors, the worse it gets. That's why most microwave and satellite receivers use a signal amplifier if there is any appreciable cable length. For serious microwave systems, wave-guide is used. It's like water pipe for radio frequencies.

Locating the video TX antenna just far enough below the aircraft to clear the gimbal would be ideal, although it isn't usually practical for every day use (unless you have extended landing gear) and most ready-made video TX antennas are too short to accomplish this. A 4 to 6 inch or so cable extension might be an acceptable option to a custom-made antenna since connector loss is actually pretty minimal. I might just try that.

Antenna Gain

Here's the big one. Antenna gain is the ability of an antenna to effectively increase its signal strength by implementing an array of single physical or virtual elements that together create the electrical equivalent of a much larger antenna. Gain figures typically correspond to TX characteristics but are used as a general rule for receiving signals as well.

First, increasing the video TX power on a drone is the least effective way of getting appreciably better range. Yes, that's a proven fact. 200mw to 600mw transmitters are completely adequate if you use the right receiving antennas. Flights of distances outside the nominal usable range of a P2 would require a different type of drone and RF transmission system anyway.

Because of the way RF works, increasing the gain of a receiving antenna by 3db is effectively the same as doubling the TX power in the direction of the gain. 6db would be the effective equivalent of 4 times the power and so on. However, you don't get something for nothing. As gain increases in one direction it drops in another. For example, a rubber duck or stick antenna that has 3db gain will implement that gain in the horizontal plain while sacrificing the same amount in the vertical plane, generally. There are ground plane and other specialized antennas that can behave differently but we're talking basics here.

As you increase gain with a directional antenna you also decrease the corridor of reception, or beamwidth. For example, the panel antenna below has a gain of 14dbi. DBI stands for Decibels over Isotropic. Isotropic means radiation in all directions equally, 0 gain or omni-directional. This antenna specs a vertical beamwidth of 30 degrees and horizontal of 45 degrees. This means that when the panel is rotated between 15 to 22.5 degrees from direct center of the TX signal source, the receive signal will drop by 3db. This antenna is from Helipal for $30.

14dbi_helipal_45h_30v.jpg


This antenna below specs at 23dbi, which is huge. That's fixed point-to-point, long-range system specs. It also has a vertical and horizontal beam-width of 11 degrees. That means you lose 3db of signal only 5.5 degrees off center. The signal would go away very quickly after that. Keeping this one aimed correctly would be tough unless you knew exactly where your drone was at all times, or had someone trying to keep it aligned for you. I'd love to build a tracking system with motorized tripod that interprets the GPS telemetry from the drone to keep the panel aimed directly at it. But I digress. Plus they're already out there if you have the bucks. This antenna is also from Helipal for $100. By the way, I pulled the images at random so no promotion going on here.

Using a diversity receiver like the Black Pearl with a lower gain antenna on the second receiver or second port is also a good idea. I'd use something a little beefier than the ducky in the picture, however. A signal amplifier in conjunction with the 14dbi antenna would probably be a safer bet for long-range video in my opinion. But whatever works, right? Just keep in mind that great video doesn't do you much good if you fly out of controller or battery range. Morbid curiosity aside, of course.

23dbi_11.jpg


I was interested in this thread because just for fun I plan to fly a slightly modified P2 to the top of a mountain near my home just to see if it can be done. The temps are too cold here now but next summer after the snow melts the game is on. One critical element of that project is to have an OSD that displays GPS lat/long in case it goes down somewhere. I use a little DVR with the Black Pearl to record video. That way the telemetry can be played back with the last known location. But let's hope that won't be necessary.




Hey Kubelwagon

That is a lot of great information you certainly do know your stuff !!

Like alot of folk on here i have went for the kits on the FPVLR website. Only thing is being in Bonnie Scotland the weather has been terrible so i have not been able to test either of them. I was just wanting to know what your thoughts were on both the fpv & tx range extender. I have put links below for both of them. Thank you.

Also can i ask Kenjancef can i ask what the 90 degree adapter you have for the immersion is called and where you got it ? Thank you

5.8GHz Premium Combo

https://fpvlr.com/store/product-category/phantom-2-non-vision/ Its the 2.4 radio control long range kit.
 
The FPVLR antennas do look to be good quality and customer reviews are very positive. Even though I just bought the Air Blades I'm going to keep those in mind since I have two P2's (one for filming and one for long range goofing off) and plan to build a Tarot 680 Pro.

What interests me the most about the FPVLR kit referenced in the link is what appears to be a longer (and thicker) cable on the white clover leaf and it already has the right-angle SMA connector. That means no adapters and the antenna element appears that it would sit a little lower to better clear the gimbal.To me that's the ideal antenna for the P2. I need to find more technical specs on it but it looks really good.

I'm sure Kenjancef will chime in shortly but the right angle adapters are simply SMA Right Angle Adapters. Most hobby stores will carry them and they're all over the place online. You just have to make sure you get the correct ends with the center pin or center hole. The male ends with the center hole are designated RP for Reverse Plug. Otherwise a standard SMA male end has the pin. The Immersion TX connector has the standard (non-RP) SMA setup, for example.

SMA_Plugs.jpg


I'm all about spending as little as possible to get the most bang for the buck but sometimes quality is more important than going cheap. Having a good video and control signal for whatever you're doing is certainly worth paying up for better equipment that works as it should.
 
Hello ,I have this set

How do you like their performance? I bought them after watching a couple videos where they were tried on a UAV with a few other popular antennas. They had the best overall signal quality in that test. I don't think they were compared to the FPVLR products, though.
 
Ok so I apologize for being a thread hog but I just checked out Dragon Link and while it's overkill for a P2, it would be great for a UAV. All I can says is...

img
 
How do you like their performance? I bought them after watching a couple videos where they were tried on a UAV with a few other popular antennas. They had the best overall signal quality in that test. I don't think they were compared to the FPVLR products, though.
Hello Kubelwagen, thanks for sharing your knowledge,This is the skyzone 600 mw tx-rx set,I m trying to find the best antennas.So far with the combination of 11 dbi panel antenna for the receiver and a 3 blade right hand polarized for the tx I got 2500 meters of crystal clear video.Thats when the Rth kicked but because I was nervous I m not sure If I was pointing correct the phantom...
 
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Hello Kubelwagen, thanks for sharing your knwoledge,This is the skyzone 600 mw tx-rx set,I m trying to find the best antennas.So far with the combination of 11 dbi panel antenna for the receiver and a 3 blade right hand polarized for the tx I got 2500 meters of crystal clear video.Thats when the Rth kicked but because I was nervous I m not sure If I was pointing correct the phantom...

I get nervous too when I try something new. I've actually been practicing with a little Syma X5C-1 with the optional FPV kit sourced from Gear Best for a grand total of around $100. Great little drone for skill building. Already modded the controller with a Taxxas antenna to increase the range to a massive few hundred meters.

The more you fly the more confidence builds. With a little higher gain antenna on the controller you should have a pretty solid system. Good luck!
 
Also can i ask Kenjancef can i ask what the 90 degree adapter you have for the immersion is called and where you got it ? Thank you

Just these, plain and simple... just make sure to check your end connectors to make sure they are the same.

Right Angle 90 Degree SMA Male / Female Adapter for Ham Radio (Qty 2)

But the new Circular Wireless antenna came with the 90 degree adapter, so all I had to do was make sure that it was SMA, which is the connector on the Immersion...
 
LoL really?
I too prefer the P2 (P2V+) over the P3. For lots of reasons, but here are some:
- P3 is new and buggy. First buyers are the ones that are doing the testing while their birds keep folling out of the sky. P2 is way better tested and debugged.
- P3 electronics is ALL ON THE SAME board!! You fry one little component (and you will) you have to buy an entire new board. P2: you fry an ESC you just buy an ESC.
- P3 camera is better? yes. But with a P2 and a zenmuse, you stick a Gopro on it and get a better camera. And you can upgrade your camera anytime. Not with the P3.
- P3 gets better range? P2 with an Itelite antenna boost gets way etter range than a P3.

These are some of the reasons I bought my second P2V+ instead of a P3.
Got the mhod to use te gopro with the DJI app so no second FPV system needed.

What mod is this?
 
What mod is this?

He converted a P2 vision + so that he could mount H3-3D/H4-3D gimbal and GoPro camera on it and use the wifi system and apps without going to a 2.4GHz FPV system.
 
He converted a P2 vision + so that he could mount H3-3D/H4-3D gimbal and GoPro camera on it and use the wifi system and apps without going to a 2.4GHz FPV system.

Ahhhh....now I wished I had gotten a P2 Vision + instead of a standard P2. Oh well.....I'm still having fun with it. Just need to figure out the FPV system later on down the road.
 
FPV does help, it's nice to see where you are, especially if you want to frame a shot. I sorta wish I got a P3A... Lord knows I've put as much money into my P2 as I would have if I bought a P3A... lol... but I'm having fun as well..
 

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