u.Fl wire antenna from u.Fl - SMA cable

End Devices (Nodes) Hardware
1

Hi

Is it a save way to cut off the SMA connector from a ufl - SMA cable and make the cable 8,5 cm long?

I don’t need a long range.

2

Theoretically you could indeed cut off the SMA and strip the wire back to leave just the exposed center conductor.

Another option could be the coaxial dipole often seen at 2.4 or 5.8 GHz, eg, you run the feedline and then you strip the end of the coax for a quarter wavelength, possible adding something like a quarter wavelength (velocity factor adjusted) of brass tube over the coax as a counterpoise up to the point where you stop the shield.

Or you could do the simple route and solder a bit of solid core hookup wire to the board

Or you could preserve your options by soldering the hookup wire to an SMA plug and screwing that into the cable.

3

Whatever solution you choose, be aware a non matching antenna (and it would be a miracle if you create a matching one without decent tools to measure if its matching) the antenna will reflect transmission energy back to the module. For a very bad match that might be nearly 100% of the energy and that might damage the transmitter. It won’t happen often but it is a possibility you need to be aware of (in my opinion at least).

4

Well if you cut the cable at 8.5cm, then you have made a cable that is 8.5cm long, success.

However, whether that is a wise or safe thing to do depends entirely on what you intend to do with this 8.5cm cable, and you have not said …

5

Thanks

I"l just buy some cheap u.Fl antenna’s for 868 Mhz.

6

The little wire ones that come with the Sodaq One are nice. I can’t find a picture or any OEM reference but they are nice and durable for swapping between transceivers on the bench.