Controlled Impedance Board-to-Board (antenna)


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.

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Its often done with U.FL (IPEX) sockets and a pigtail lead with U.FL plugs on each end.

Something like this:

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Example picture:

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@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 :slight_smile:

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.

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