If you take a look at our review of the Wilson DT4G signal booster you’ll see that one end has a standard F connector and one end has a slightly smaller, thinner connector. That smaller connector is an SMA connector and it’s used where you need similar performance to the regular F connector in a different package.
Remember, this stuff comes from engineers, and the full name of the SMA is “Radio Frequency connector, Subminiature, type A.” It was developed to have the same qualities as the F connector that’s used for most coaxial cables but to be a little smaller. It’s hard to know why those engineers really felt the world needed a slightly smaller screw-on connector, but they did.
Because the SMA connector has the same performance as an F connector, it can be used for the same kinds of signals. Because it’s smaller, it won’t attach to regular RG6 cable, so it can really only be used for short runs of thinner cable. This makes it perfect for things like inside antennas for cell boosters.
Wilson uses the SMA connector to make it easy for you to know which side the indoor antenna connects to. zBoost uses the TNC connector for the same purpose; it doesn’t make much of a difference at the frequencies that are used for cell boosting.
So it really boils down to the SMA connector being there to help you figure out how to hook things up quickly, and anything that makes life easier for you can’t be bad.