Ground plane antenna for LORA/Meshtastic

Edit 24-06-15: I found an error in one of the files!!! The console/standoff part was not hollowed out to fit the antenna. Now reuploaded.

This antenna can perform very well if tuned properly.
You will benefit greatly by using a NanoVNA or similar analyser.

Google DIY ground plane antenna.

Not very useful for portable applications but great for a discrete base station.
FreeCad source file included.

Parts:
1.5 mm2 single-strand copper cable - with insulation - making the diameter about 2.4 mm.
Connector that fits your radio (Male SMA for Meshtastic devices).
RG58 coax cable.

Assembly:
Cut 5 lengths of the 1-strand cable. Length depends on the wavelength; should be about 1/4 of the wavelength for the top antenna part, and slightly longer for the 4 groundplane parts. For 868 MHz this will be something like 90 mm for antenna and maybe 100 for the groundplane as a starting point.

Remove insulation from the RG58 and solder one end to the connector, inner pin to center wire, ground (outer) to screen braid.

Thread other end through antenna main part and solder the 4 GP wires to the braid and the antenna wire to the center wire.

Push GP wires in the slots and place the protective top part over it (antenna wire threaded through). All wires shuld be as straight as possible.

Tuning:
Antenna is tuned by gradually shortening the wires and measuring the SWR with an analyser such as a NanoVNA. I got 1.2 to 1.3 which is quite good (should be below 2). Some experimentation is required. It is good to start with wires that are a bit long.

RG58 should be as short as possible to minimize signal loss. Mine is ~1m.