Hello,
Here a tutorial video to build your own Meshtastic dipole antenna (868 Mhz).
This antenna will have a VSWR of 1.2 or less which is way better tuned for our Meshtastic frequenies than any commercial antenna you may buy on amazon or aliexpress. It is also way cheaper and easy to build.
Hope this will motivate and help you build your own.
Cheers
good tutorial, thanks for that. It is also important to mention that polarization, i.e. the horizontal/vertical orientation of the antenna, plays a major role. If the dipole is held horizontally, there will be polarization loss to most nodes since they use a vertical antenna. I have to try to get all of my home-made CB radio antennas to the size of 868Mhz. A T2LT would be a good start, even if the standing wave barrier still needs to be calculated. Greetings from Switzerland
Yes that’s important to say : use your dipole vertically (assuming most antennas are also vertically polarized)
SWR is important but I think directive gain (radiation pattern) is also an important factor. In my understanding a standard dipole is just the base line for this. So it’s not just about return loss.
A dipole 's radiation pattern is more or less a slightly flattened donut perpendicular to the antenna elements, with its center at the feeding point (intersection of the coax and perpendicular elements). The gain of a dipole is ~2db and is omnidirectional.
For a relay node or an all purpose mobile node, an omnidirectional antenna is probably better. For that a dipole antenna is a good choice. On the contrary if you’re looking for a directional antenna, you should not use a dipole but rather typically a “rake” type antenna.
I was thinking more about different or more concentrated angles in the vertical plane (horizontal omnidirectional but more horizontally concentrated energy, avoiding cloud-burning). In practice there are many interacting factors that can influence the effectiveness of an antenna in a given situation. But that’s part of the fun (at least for me) to experiment with.
What would the effect be if the feed cable ran back along one of the dipoles instead of exiting at 90 degrees? Would that essentially give the same performance as snipping the outer coax and leaving 80mm of inner cable hanging out?
I have to make something that has a thin hanging wire type of antenna (for weight and ruggedness) so I am trying to figure out what the most effective way to do this would be.
Thanks
that would impact the radiation pattern and impedance. What you are looking for makes me thing of a “V antenna”. Look up for V antenna builds on youtube, you’ll find some tutorials (look for the IBCrazy channel. He’s a guy who published mots of antenna DIY builds tutorials for drones but you can transfer the application to meshtastic frequency bands)