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I'm working on a project in microfluidics and it has become apparent that a significant challenge to overcome is a lack of consensus in connector design.

I have been thinking about my time working with microwave filters and the fact that the vast majority of devices were connected to the VNA with SMA connectors.

My question is, what was the driving force behind that design becoming the standard?

Any insight or history would be appreciated.

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  • $\begingroup$ I'm no expert in connections, but I'd say that SMA connectors just make sense - they can easily be waterproofed (like on my Yaesu VX-6R), and they are the perfect size for small radios, for a couple. I would think that impedance would also have an effect on the choice. $\endgroup$
    – Galaxy
    Nov 22 '20 at 23:04
  • $\begingroup$ Hello and welcome to ham.stackexchange.com! $\endgroup$
    – rclocher3
    Nov 23 '20 at 17:28
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I wouldn't say that SMA is "the" standard RF coaxial connector, I would say that it is one standard among many. No connector has emerged as the best for all uses, which is why there are many standards. Other connectors such as the "UHF" (badly-named because its performance is terrible at UHF), BNC, F, and N connectors were invented earlier, and these that I mentioned are still in wide use.

I wasn't there when the SMA connector was invented, but I'll guess that the designers had in mind a small and inexpensive connector with a low insertion loss up to frequencies of a few gigahertz. The SMA has shortcomings for sure, such as not being able to handle lots of power, but the designers surely assumed that users needing better power handling, for instance, would just use a different connector. People have voted with their money and made the SMA connector a resounding success, just as other connectors have been successful for other niches.

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  • $\begingroup$ Thank you for your answer @rclocher3 I agree it is one standard, I'm trying to focus on what you touch on in the latter part of your answer, was there a particular company or supplier of particular equipment that favoured the design over others if indeed there were other designs. $\endgroup$ Nov 23 '20 at 19:18
  • $\begingroup$ Actually, having thought about your answer again, you do answer my question perfectly and have given me something to think about. $\endgroup$ Nov 23 '20 at 19:24
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    $\begingroup$ I'm glad that I was able to answer your question! By the way, it is often a good idea to wait a while (I've waited as long as two days) before marking an answer as accepted, in the hope of continuing to attract answers. $\endgroup$
    – rclocher3
    Nov 23 '20 at 19:31
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    $\begingroup$ Note en.wikipedia.org/wiki/SMA_connector, particularly the pictures of subtly different competing connectors. $\endgroup$
    – Jon Custer
    Nov 23 '20 at 20:44

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