Advice > 22GHz SMA "through wall"   - Page 1
Forum section: electronics / rf-microwave

author: prutser
author_rank: Regular Contributor
timestamp: September 21, 2024, 07:25:58 pm
content: I was looking into some milled housings for some small RF modules. (amplifier, mixer, ... ) on Ebay and some Chinese shops you can some some filters, bias Tees, which are in milled housings with (flanged) SMA connectors. The SMA connectors are not really suitable for frequencies above 10GHz, so I was looking some some other types, preferable usable up to 23GHz.The main difficulty seems the wall thickness of the housing (4mm), this will require 4mm dielectricum and approx. 2mm pin length. Pin will be soldered directly onto a GCPW.So far I was not able to find a flanged SMA (2 screws) with extended dieelectricum specified above 18GHz. (Found one from "Delta", but seems not available)Someone has a suggestion how to del with this ? SMA with long pin "though air" instead of PTFE ? Or are there any other options ?

author: joeqsmith
author_rank: Super Contributor
timestamp: September 21, 2024, 07:30:30 pm
content: https://www.mouser.com/datasheet/2/704/03K721_40MS3-3475174.pdf

author: prutser
author_rank: Regular Contributor
timestamp: September 24, 2024, 06:17:13 am
content: Thanks for the reply. It's an interesting connector. I had to do some searching to find out how it's used. It does however not was I am looking for. The center pin has to go though 4mm aluminium, so probably it must be something with extended dielectricum. I could find only one which goes up to 26G (From Delta) but it seems obsolete.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 24, 2024, 12:47:03 pm
content: You could have posted sketches, part numbers of what package you were considering but chose to go with as little information as possible. So, if you want SMA but higher grade, go with 3.5mm. These will get you to the frequency you want. Of course, you will need all the interconnects to be 3.5 as well. Cost isn't too bad.***Just visit Digikey or Mouser and sort for 3.5mm to get a quick idea of what is available and the cost.

author: RadioNerd
author_rank: Regular Contributor
timestamp: September 27, 2024, 07:59:08 pm
content: This kind of feedthrough is usually not limited by the SMA connectors themselves (although I agree that they are not of the best quality...)The crucial factor that is often neglected in these boards is a proper low inductance ground connection between inner wall of thd housing and and the PCB inside.one screw in each corner will just not do the job above 6 GHz or so.I would therefore not expect better performance by using 3.5mm or even 2.92 mm connectors...

author: mwbajor
author_rank: Newbie
timestamp: October 05, 2024, 04:34:18 pm
content: Are you dead-set on SMA? If you don't need a water-tight seal you can look into SMP and mini-SMP connectors.

author: prutser
author_rank: Regular Contributor
timestamp: October 15, 2024, 05:06:48 pm
content: Thanks for the replies. I didn't consider it, but indeed the inductance with 4 screws might become problematic. I probably better changed to edge launch connectors. Only have to find a nice way to use them in a shielded case.