I tried to make a 5/8 wave length ground plane antenna for Meshtastic, I had one N-connector for that one left.
82mm for the radials, 205mm (start with 1 cm more and cut later) for the straight radiator and 2 windings around a pencil as a matching coil (the wire was 270mm in total I think).
The NanoVNA showed a SWR about 1.07 at 868.5 MHz and a short walked confirmed a good signal:
Distance: 931m
SNR: 5.50 dB
RSSI: -86 dBm
Later I will go further.
Very thankful after days of high winds to get a fairly low wind day in time for the Indy 500 so I can watch the race with my digital antenna instead of having to deal with the Fox Sports app I hate worse than anything on Earth.
Free stainless steel garbage cans around here. I am so tempted to make this into a dipole antenna, so I can call it a "trash can antenna".
(If you have a couple of spare Cybertrucks, we could do the same thing, but on lower bands).
Wow! Finished building my first 868 MHz ground plane antenna for Meshtastic!
Still needs SWR measuring with a VNA and maybe shortening a bit, which will be my first time doing that, too.
For a test it already got too late but I will keep you updated about the results. Also I would like to try different antenna designs, it's quite fun!