Flange mount SMA connectors - How do I connect the ground  - Page 1
Forum section: electronics / rf-microwave

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: February 08, 2018, 02:01:43 pm
content: So I got myself some enclosures to try and use for some RF projects (alu diecast boxes from hammond).Now I would like to look at connector options. Ideally, I want to use the flange-mount connectors, as seen in the picture below. However, I wonder how I should properly connect the ground. The examples only show the center conductor that can then be soldered down to the PCB. How do I properly connect the ground to ensure the system keeps a nice 50 ohm environment and behaves well? I would like to use these connectors since that way there is as little strain on the solder joint when making the connection.Or does anyone have any good whitepapers on the different ways to connect RF connectors to PCBs? I'm used to the side/edge launch connectors that transfer to a CPW mode, but I don't know how to work with these connectors.

author: tggzzz
author_rank: Super Contributor
timestamp: February 08, 2018, 02:13:24 pm
content: Such information will be on radio amateur's websites and publications. Look for ARRL and RSGB handbooks; obviously you won't need to get the latest version!

author: Jesset1996.5
author_rank: Regular Contributor
timestamp: February 09, 2018, 12:48:30 am
content: You could make a pad for it on the pcb to solder it to. You could also include holes on the pcb to bolt it down This way you can keep the stress off the pcb trace. Flux should be used to get a good solder joint. The flux in solder is OK but for this application but your better off applying flux before soldering in this application. Just be sure to use electronics grade rosin flux. I know a few people who used flux made for plumbing for things like this.It didn't look too great a month later as the entire pcb had corrosion issues due to them using acid flux which is made for plumbing not electrical work of any kind.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: February 09, 2018, 07:13:51 am
content: Quote from: tggzzz on February 08, 2018, 02:13:24 pmI'll look into them, thanks!Quote from: Jesset1996.5 on February 09, 2018, 12:48:30 amTo solder the ground to? but how? I must be missing something. I can see how I can get a good connection to the center pin but in order to maintain a nice 50 ohm path I have to get the ground at the same place too?Or are these connectors limited to micro strip mode cases where you use the case to provide ground though the bolted connection?

author: hagster
author_rank: Frequent Contributor
timestamp: February 09, 2018, 08:34:30 am
content: I don't know of a good way to attach those if you need it to work at high frequencies. They can be used for connecting to patch antenna elements as an example, but generally I would ignore them.You can get connectors like this with cable crimps on the rear if you really need the 4 mounting screws. However, I find these are almost impossible to drill and tap accurately enough by hand. If you have CNC then maybe it's easier.

author: yl3akb
author_rank: Regular Contributor
timestamp: February 09, 2018, 01:07:06 pm
content: These type of connectors often are used together with milled enclosures where enclosure wall forms coaxial shield. Like here for example: