Where to place the antenna?

[thijmen5]

Hello,

I have a selfmade wookong octocopter and placed an 25mw 5,8GHZ vtx (stock antenna) on it. But every time I turn my copter the reception is getting real bad. (landing gear gets in front of the antenna beam)

Where do you guys place your antenna? The best is to mount it very high or low, but both are no options.

Will an upgrade to 600mw improve it? Or am I only getting better reception at further distances?

Regards,
Thijmen

 

[RTRyder]

Hello,

I have a selfmade wookong octocopter and placed an 25mw 5,8GHZ vtx (stock antenna) on it. But every time I turn my copter the reception is getting real bad. (landing gear gets in front of the antenna beam)

Where do you guys place your antenna? The best is to mount it very high or low, but both are no options.

Will an upgrade to 600mw improve it? Or am I only getting better reception at further distances?

Regards,
Thijmen

Couple of things come to mind, first is that a 25mw VTX doesn't have a lot of power so unless everything about your setup is perfect you aren't going to get all that much range. Second is using the stock whip antennas on both the transmitter and receiver you're also limiting what the system can do, a set of RHCP (Right Hand Circular Polarized) antennas will help, they won't necessarily increase the range but you will see a much better signal at the range the TX is capable of.

The other consideration is one that I believe you already know and is especially true for the 5.8 frequency, it needs a clear line of sight for best reception so if your antenna is mounted in a way that blocks the LOS between the two antennas then you're going to have problems, more so if the obstruction is made of carbon fiber.

A stronger VTX will help somewhat but the main thing is to have a good antenna on both ends and keep them as obstruction free as possible.

Here's an example of what I had to do to eliminate GPS interference on a DJI F330 frame, also helped the reception by getting the antenna up and away from the frame itself...

Here's a similar setup on my QAV500 but this one I just finished changing to a set of the Immersion Spironet RCHP antennas and the antenna is much lower and bit further back on the frame, haven't had an opportunity to distance test it yet but so far it seems to work fairly well in backyard testing. The TBS Disccovery on the right has the VTX mounted on the top deck and the antenna is directly mounted via a 90 degree adaptor. This is a 1.3 gHz 1500mw system and I don't have much of any problems with reception on this setup and all of the antennas you see on it other than the GPS were made by me.

You're only limited by what you have the capability to do, I make my own antennas and cabling so I can fit them anywhere I need to. You can still be creative using off the shelf components from any of the FPV specific vendors, I highly recommend ReadyMade RC for great service and just about anything you could want FPV related.

Ken

 

[thijmen5]

Thanks for your comment!

I might create my own antenna's and try it first on the 25mw (because we need to have a license here). Do you find any interference between the GPS and vtx? If I set my vtx antenna up high I need to be sure it doesn't interfere with the GPS.

 

[baker55]

Ken on your 1.3 where did you get your antenna and what type do you have on your base receiver? Shaun

 

[RTRyder]

Thanks for your comment!

I might create my own antenna's and try it first on the 25mw (because we need to have a license here). Do you find any interference between the GPS and vtx? If I set my vtx antenna up high I need to be sure it doesn't interfere with the GPS.

I doubt you'll have much trouble with the 25mw VTX on 5.8 but as a general rule try and keep the video and GPS as far apart as possible. Some GPS units are more sensitive to interference from the VTX than others and some frequencies for transmitting video cause more interference than others, 1.3 often being one of them.

Ken on your 1.3 where did you get your antenna and what type do you have on your base receiver? Shaun

The antennas I made, they're basically the IBCrazy CP design with the Skew Planar Wheel on the receiving end. I started building them out of necessity after a low hanging tree branch grabbed the first Bluebeam 1.3 that I bought and handed it to a spinning Graupner prop, what remained of the antenna was found about 15 feet from where the quad went down. I was on vacation that week and the only way I was going to be able to continue to fly that setup was to make a replacement so I grabbed the roll of wire off my MIG welder and gave it a shot. I was pleasantly surprised when it worked just as good as the one that got trashed so from then on I decided to make them myself and save a pile of $$. Once you've done a couple it gets easier to make them and the lower frequencies are bigger and more forgiving than the 5.8 so seem easier to make overall.

Ken