- for FCC 915MHz it is 75mm
- for EU/LBT 868MHz it is 80mm
From time to time FrSky has a big problem with cutting their antennas to a correct length. Good thing, you can make your own TBS Crossfire RX antennas for cheap!
As you might have realized, from time to time I’m making an antenna and I have the equipment for it. I’m also strongly considering to produce a small batch of antennas for FrSky R9 long-range radio system since there is a high demand for such antennas.
I have made a first small series or FrSky R9M dipoles tuned for the 868MHz EU-LBT version of this radio link and I want to give away 3 of them to my Patrons. If you want one of the 3 antennas:
On that day I will randomly choose three commenters and send them brand new, custom made 868MHz FrSky R9M antenna.
FCC 915MHz version giveaway will follow, I’m waiting for parts to arrive in a few weeks.
Details for halfwave dipole for an 868MHz band are quite simple:
Moxon antenna in layman terms, it’s probably a simplest linearly polarized directional antenna. It’s like a bent halfwave dipole with a bent reflector in a back. Think about it as a very simplified Yagi antenna. It does not have much gain but has very good backward rejection. And thank’s to a simplicity, Moxon is super easy to build at home. And I’m proud of radio carrying handle snap mount. I think I did a good job over here.
I’ve built mine with some 3D printed parts, 0.8mm copper welding wire, 22cm of RG174 coax and RP-SMA plug. And some glue of course! Result? It’s definitely directional 🙂 I’m not using it very often, but it’s small enough to be taken everywhere where I take my X10S.
Cloners gonna clone and chinesium keeps being chinesium! It did not take long for Banggood / Realacc to clone Lumenier AXII FPV antennas and call them Realacc UXII circular polarized FPV antenna. Coincidence? I do not think so.
I've ordered few of those in December, they arrived last week and this is what came in package
Unfortunately, in this case, the build quality was typical chinesium. As soon as I opened one of them, antenna disintegrated… oh bugger…
I only hope the other (the one I did not open) works like expected. I did not test them in real life conditions since the weather is rather bad over here. This weekend maybe… In a meantime, here is a video of what is happening inside Realacc UXII 5.8GHz antenna.
Today another video tutorial. It’s just simpler to show how to make something on video than with text and images. So, without further ado: How to make Inverted Vee antenna for 5.8GHz FPV at home. All that is required is:
At the end we have small and light FPV antenna that just works. Sometimes it’s just worth to make something by yourself, right?
It’s still middle of winter here in northern hemisphere, but I’m slowly preparing for next flying season. One of my goals is to push my DIY HC-12 Telelemetry System to a next level. In both range and quality. For quality I’m planning small hardware LTM decoder with LCD. For range, I want to reach at least 1.5km with 9600bps FU3 mode and 2.5km with 1200bps FU4 mode.
Radio range of my first drone, UDI 829A was pretty pathetic. OK, it was (still is, I only have to finally replace motors) pretty indestructible, quite stable and reasonably priced. But effective radio range as quite short. More less 50 meters. Above that limit strange things started to happen. The reason was pretty simple. Just take a look at this picture.
Can you see the transmitter antenna? Yeap, that it this short cable. Not only it does not go into “antenna cover” of the receiver, it is also horizontally polarized and when receiver is held in a normal way, pointing into a drone, it emits almost no signal in this direction. This and an additional single whip antenna on the receiver makes it virtually impossible to have a good radio range.
So, I’ve decided to fix that and install external antenna that would work with vertical linear polarization and actually emits some power in drone’s direction.
This tutorial shows how to do it for UDI 829A, but will work almost all cheap drones. Their transmitters are very similar inside and as long as there is antenna pad or connector, it can be done. Continue reading “Improving cheap radio range” »
Most people in RC hobby knows that receiver and transmitter antennas should match polarization. But what would happen if there was a mismatch? For example when transmitter uses linear vertical and receiver circular left hand? There would be a loss of power, attenuation. How much? Look at table below. Remember: -3dBi means half of power is lost during polarization change and you need +6dBi power (4 times more) to increase range by factor of two.