I am studying microwave engineering at university, but I never had a possibility to try to manufacture anything that I have been learned in my courses.

So I have decided to try it by myself. I have chosen a directional bridge at 10 GHz and I have managed to model it CST. But now I have encountered a selection of coaxial connectors, which seems to not be that easy.

I know that the main parameters are:

  1. input impedance,
  2. frequency range.

But when I started selecting some particular connector I have found out that there is something called coaxial termination, see https://uk.farnell.com/c/connectors/rf-coaxial-connectors-accessories/rf-connectors. I have been trying looking for more information on how to select the right type or what does each type name (e. g. crimp or clamp) means. However, every time I have tried to Google this I have only came to the term termination used in sense of input impedance.

I have also tried to search for some directional bridges on the Internet and I have found out this one. enter image description here

I know I could try lookup for some similar connectors at the link above, however, I do not want to select just some random look-alike connector.

I want to ask you please for help, what are additional criteria for connector selections and if there is any cheatsheet or any other kind of help which described stated connector termination types.

The circuit I am trying to synthesize would not be part of any other system or component. It is just a sole directional bridge.

Thank you in advance for any advice.

  • \$\begingroup\$ Be clear about what your question is. I've read it twice now and I'm unsure what your question is. This is a Q and A site and should not be used to solicit opinions. \$\endgroup\$
    – Andy aka
    Aug 8, 2021 at 11:29
  • 2
    \$\begingroup\$ I am not a native English speaker so I am afraid that some sentences and phrases may not be well understood. My question is particularly about additional criteria in the selection of connectors (in addition to input impedance and frequency range). Can you please tell me which part of my question reduced its readability? I could try to fix it. \$\endgroup\$ Aug 8, 2021 at 11:53
  • \$\begingroup\$ Try searching with the term "mounting", instead of termination. I know SMA connectors are available with all types of mounting options, including the board edge type you showed, chassis mount, through-pcb, etc. \$\endgroup\$
    – SteveSh
    Aug 8, 2021 at 11:54
  • 1
    \$\begingroup\$ Humphrey Appleby is a name of a character in "yes minister" and "yes prime minister" and, he was well-known for his overly verbose way of saying things. Please don't fall into the same trap. Concentrate single-mindedly on what your question is. This is a Q and A site. \$\endgroup\$
    – Andy aka
    Aug 8, 2021 at 12:01
  • \$\begingroup\$ Andy aka: I will try to be more specific next time. I was trying to follow the quick with three steps tutorial which was shown to me when I had started asking this question. But I admit that I might not did it the best way. SteveSh: Thank you. This is that term I have been looking for. \$\endgroup\$ Aug 8, 2021 at 18:07

3 Answers 3


For 10 GHz with SMA plugs your best bang for the buck is to choose semi-rigid coax. These can be pre-made or make your own with semi-rigid copper coax soldered to shell.

Then choose SMA PCB mount female in straight or 90 deg for your board type , e.g. PTFE (better) or FR4 depending on loss tangent. Look for frequency Ratings ($) and use calibrated torque tool to tighten without thread damage.

Unfortunately there is a wide range in quality which is not easy to see from any photograph. Many are rated for 6 GHz will not perform well.

enter image description here

Some have a bulkhead thread for metal enclosures which may improve results. Some Uni’ designs I have seen for Spectrum Analyzers even had the alum. machined enclosure flash gold plated.





On the Farnell site, you want to display the 'Extended Attribute' for 'coaxial termination', so that you can compare the name with the picture. Then you can 'filter' the termination type that matches the picture you want.

Farnell calls the type of termination you have displayed in the picture in your post a 'board edge' termination: it is designed for terminating a coaxial cable on a board edge.


I have been trying looking for more information on how to select the right type or what does each type name (e. g. crimp or clamp) means.

David's answer told you that the type of termination you are looking for is "board edge" or "end launch".

It's worth adding that crimp and clamp terminations are ways of attaching a coaxial connector to a coaxial cable. That is, they apply to the connector that's part of the cable assembly, not to a connector that's mounted on a circuit board. Therefore you can ignore these type of connectors entirely for your design.

if there is any cheatsheet or any other kind of help which described stated connector termination types.

You can look at the datasheets or customer drawings for examples of each type of termination you're interested in. That should give you a fairly good idea what is meant by each term.

In case the drawings aren't clear (and sometimes they aren't if you don't know what you're looking for), you can visit the manufacturer's web sites and look for assembly instructions for different types of connectors. Those should make it much more clear how each type is meant to be used (assembled onto a cable, soldered onto a board, etc).


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