DIY Yagi Antenna Sends LoRa Signals Farther

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.

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Hiking Pole Turned Lightweight Yagi Antenna

Among amateur radio enthusiasts, there’s a subset of users who climb mountainous areas to use their gear from elevated positions. Anyone looking to take part in what’s known as Summits on the Air (SOTA) will obviously want to keep their equipment as light and small as possible. For [Stuart Thomas], that meant a collapsible yagi antenna he could easily pack away.

But one day he wondered why he was carrying around a separate antenna boom when his aluminum hiking pole would make a perfectly good substitute. All he had to do was figure out a way to mount the elements to the pole in a way that could be easily assembled in the field. He initially tried to use the sort of insulated electrical clamps used to hold down conduit, but he found they weren’t quite what he was after.

[Stuart] eventually ended up designing and 3D printing his own element mounts that use an M3 bolt to tightly clamp onto the hiking pole, preventing them from twisting while still being very lightweight and easy to adjust. To further reduce the packed size of the antenna, he cut each element in half with a pipe cutter and flared the ends slightly so he could reassemble them on location with inserts.

Even if you aren’t the type of person who owns hiking poles, let alone climbs mountains for fun, there’s still plenty of interesting applications for a lightweight yagi antenna. We’ve seen custom yagis built out of carbon fiber before and of course cobbling one together out of PVC and tape measures is a classic hack, but we think the solution [Stuart] has come up with strikes a nice balance between the extremes.

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A Simple Yagi Antenna For Your Wi-Fi Router

When we take a new Wi-Fi router from its box, the stock antenna is a short plastic stub with a reverse SMA plug on one end. More recent and more fancy routers have more than one such antenna for clever tricks to extend their range or bandwidth, but even if the manufacturer has encased it in mean-looking plastic the antenna inside is the same. It’s a sleeve dipole, think of it as a vertical dipole antenna in which the lower radiator is hollow, and through which the feeder is routed.

These antennas do a reasonable job of covering a typical home, because a vertical sleeve dipole is omnidirectional. It radiates in all horizontal directions, or if you are a pessimist you might say it radiates equally badly in all horizontal directions. [Brian Beezley, K6STI] has an interesting modification which changes that, he’s made a simple Yagi beam antenna from copper wire and part of a plastic yoghurt container, and slotted it over the sleeve dipole to make it directional and improve its gain and throughput in that direction.

Though its construction may look rough and ready it has been carefully simulated, so it’s as good a design as it can be in the circumstances. The simulation predicts 8.6 dB of gain, though as any radio amateur will tell you, always take antenna gain figures with a pinch of salt. It does however provide a significant improvement in range, which for the investment put in you certainly can’t complain at. Give it a try, and bring connectivity back to far-flung corners of your home!

We’ve covered quite a few WiFi Yagis here over the years, such as this rather extreme wardriving tool. But few have been this cheap.

Thanks to London Hackspace Radio Club for the tip.