RF: Silly U.FL to SMA pigtail question

[rthorntn]

Hi,

I'm messing about with LoRa, so I have a radio connected to a Pi, does the threaded SMA connector on the pigtail actually have to be secured to metal to form any part of the connection, I don't think it does but the question is niggling at me?

Thanks.

[tooki]

If you are using a metal enclosure for shielding, then you’ll want for it to make contact so the case will act as a shield. The antenna will work regardless of how the SMA is mounted.

[bson]

It doesn't, although if you have an enclosure it's a good idea to use a nut just to hold it in place.  If it's a metal enclosure it's probably already grounded so will act as a shield (and if not grounded, make sure to do so), and adding another path between ground and the antenna isn't going to make much difference.  The SMA plug will only use about half of the available thread.  Note that SMA has a torque spec, which for casual applications like this can be stated as "until you feel resistance with a 3 inch spanner wrench", ballpark speaking.  Err on tightening lightly.