LoRa gear can be great for doing radio communications in a light-weight and low-power way. However, it can also work over great distances if you have the right hardware—and the right antennas in particular. [taste_the_code] has been experimenting in this regard, and whipped up a simple yagi antenna that can work at distances of up to 40 kilometers.
The basic mathematics behind the yagi antenna are well understood. To that end, [taste_the_code] used a simple online calculator to determine the correct dimensions to build a yagi out of 2 mm diameter wire that was tuned for the relevant frequency of 868 MHz. The build uses a 3D-printed boom a handle and holes for inserting each individual wire element in the right spot—with little measuring required once the wires are cut, since the print is dimensionally accurate. It was then just a matter of wiring it up to the right connector to suit the gear.
The antenna was tested with a Reyas RYLR998 module acting as a base station, with the DIY yagi hooked up to a RYLR993 module in the field. In testing, [taste_the_code] was able to communicate reliably from 40 kilometers away.
We’ve featured some other unique LoRa antenna builds before, too. Video after the break.
Further – Unless my Dad is extending the signal range!
https://www.youtube.com/watch?v=exCYSfQod14
Good start. Now add a balun, then stick it on a VNA and learn the joy of a gamma match. Then fine tune the element lengths.
Betcha there’s at least 3 dB sitting on the table.
Really difficult to get a gammaatch right at those frequencies because the dimensions are tiny and critical. Far easier to match it with a coax transformer
Tiny? looking at the one sitting on the bench next to me: This one is 27 mm long, 12 mm spacing, with 2 mm conductors.
Coax transformer is great for production, once you get it dialed in, but it’s pretty easy to adjust a gamma match — just loosen and move the screw clamp. A coax transformer is not as easy.
Print it on a PCB people
Before using one it is worth checking if local regulation don’t limit the ERP which is common on ISM bands. Even with limited output power a directional antenna can improve connectivity by improving SNR at the receiving end.
My Lora installations were reaching nodes three or four hundred kilometres away with off the shelf antennas.
And…
I’m pretty sure this was substantially cheaper.
And? No and. Just that 40 km is not very far at all. I’ve had farther than that with the bent wire on a Semtech module.
Our company supports LoRa WAN for some of our customers, and when we first started working with it, we went crazy trying to achieve isolation in the lab, even inside RF shielded boxes. The sensitivity on those modules was mind bending. Easily a hundred feet with no antenna installed at all, just leakage out the connector. We have seen 15 KM in the field with a simple rubber Omni.
Does a $40k motorcycle you can buy “off the shelf” go faster than a bike you can build from spare parts and a $100 trip to a hardware store?
What do you mean “No and”?
Yes and.
As in, “your comparison is unimportant in the context of this article”
Unless your “off the shelf” antenna is $1 and available everywhere, it means nothing in the context of the article.
And even yen, buying it would rob some users of the education of learning how to make it, and the experience of actually doing it.
No that’s over mqtt
slow news day when a yagi antenna is headlined.
LoRa? Does that mean this is meshtastic capable? Thanks
Yes.
actually was going to watch video but it is 32 min long and contains paid promotional material. So I’ll be annoying and ask- did he compare that antenna to… not that antenna? I was under impression LORA was optimized for low power, long range (LoRa…. right in the name) so 40km may not be that impressive.
In any case that little antenna is pretty adorable actually.
73
It is quite cute!
Hmmm.. There is really nothing special about antenna gain, modulation coding and distance. The two primary limits for limitation of coverage distance are terrain blockage (earth curvature, dirt or buildings in the way of the signal, atmospheric refractivity index) and localized interference generated by other transmitters or noise sources.
Inmarsat has no problem at all communicating 23,500 miles from earth to space and (additionally 23,500 miles) back with 400 milliwatts and a low gain, nearly omni directional satphone antenna. (at 2 GHz)
Yes antenna gain improves the signal strength. Antenna directionality improves the discrimination of localized and distant received interference. Reduced bandwidth and forward error correction (LoRa) improves transmitted power spectral density and reduces the received signal strength requirements and carrier to noise and interference thresholds.
The claim that any magic antenna gets you a radio path of XX miles is more about anecdotal terrain and obstruction loss between the endpoints and how quiet the interference is at the 2 locations.
Signal strength is predictable. It takes 6 dB to double the distance, given equal modicods and C/(N+I). (20 log(10) distance)
Nice article about building a Yagi antenna.
The premise that it will give you X miles of coverage distance, though,….
There’s no reason that this Yagi antenna on LoRa couldn’t communicate 150 miles between 2 radio quiet 5,000 ft mountain tops.
Good effort for a home brew antenna however the unobstructed line of sight, especially at UHF frequencies, will be king here.
Thank you for this article, i am wanting to learn more about how radio frequency technology works. i find every comment insightful, and i learned more in 10 comments than i would sitting in a classroom for 4 years. I aporeciate this article and i appreciate those who took time to leave comments. Thank you all.
Is it CB radio signal or Ham radio ? Depends on use TV’s don’t need antenna’s anymore because signal(I think from 2008) is digital not analog .
I have a rooftop tv antenna that i bought 25 years ago 9n a 5ft mast that gets almost 40 channels. They still work
Ease up on the snark, people. This is hackaday, where people show what they’ve built using available tools, materials, and their cleverness and initiative. You might politely point out another way of doing the same thing, or just say well done.
The video image is wrong – you want to use a yagi vertically. I got about a dozen yagi antennas with a bunch of other gear a business was getting rid of. Works great for a helium hotspot. In my area almost all other ones are in a 60 degree window, and 7 to 25 km away. The beam width of the yagi apmost maches that exactly
Vertical? You don’t antenna do ya?