hi!
i have book looking at a way to run a board-to-board connect, like the ones you see on a Raspberry Pi Compute Module 4, but with controlled (50ohm) impedance for an antenna - the intention is to have the antenna on the main board and an RF module on a daughter card - have been reading up a bit, but nothing has fallen from the google-tree-of-knowledge yet!
I would think that the better way to do this is a UFL antenna connector on both boards and a small coax in between. Or direct from the daughter card to the antenna which could be better placed than being on the mainboard.
Its often done with U.FL (IPEX) sockets and a pigtail lead with U.FL plugs on each end.
Something like this: https://uk.farnell.com/molex/73412-0508/cable-assembly-plug-plug-50mm/dp/1340201
@ToyBuilder / @DefProc thanks, that’s what I had expected (esp. since every board I have does that in one form or the other) - I have this OCD type desire for things to be neat and clean! So, routing the antenna through a board-to-board would just make for a clean design, especially when swapping daughter-boards, there would be no pigtail to worry about for the user, just swap a module out.
though the use of a pig tail does carry some advantage in that I could use a uFL → SMA pigtail if required to support multiple antenna variants as well. The other option I am thinking about is to put a chip antenna on the module daughter board itself, though I am not sure how well that will work with clearances, ground planes etc, perhaps if i package the antenna at the very edge of the host board with suitable clearance and ground planes… or, just do it as @ToyBuilder has 
These might also be a solution: BM56 series - HIROSE Electric Group [Connector]
Never used them personally but stumbled on them for other reasons.
I’m not sure if this is applicable or completely off the mark, but there are RF pogo-pins out there.
https://www.jyprobe.com/RF-Test-Probes.html
Hope that helps.
@LukeBeno that looks like the exact same connector i found, not sure why i didn’t add it to the post!
@seth.kazarians those look really cool - probably not useful for my current application which requires more mechanical stability, but otherwise interesting for the future
