What Are SMA & RP-SMA Connectors and What’s the Difference?

Here at LinITX.com we’re often asked by customers about SMA connectors and RP-SMA connectors (sometimes referred to as RESMA connectors) – specifically, which connectors they need and what’s the difference between them.

Here’s a quick guide to SMA and RP-SMA connectors.

The SMA in SMA connector is short for SubMiniature version A, and the RP in RP-SMA or the RE in RESMA connector is short for Reverse Polarity.

So, we have 2 connector types: SMA, and the reverse polarity version which has 2 names: RP-SMA and RESMA – these both refer to the same connector type.

Most of our customers purchasing SMA and RP-SMA connectors are using them with mobile and WiFi antenna systems, LTE routers and 3G/LTE/4G WiFi devices including Teltonika 4G LTE Routers, MikroTik LTE 4G 5G, RF Elements Antennas, Ubiquiti LTE and more – although SMA connectors and its variations have multiple use cases, including hand-held radios, microwave systems, USB software-defined radio dongles, and in radio astronomy, most commonly at higher frequencies (5 GHz+).

It’s also worth noting that RP-SMA and RESMA connections tend to be used on WiFi antennas, whereas SMA connectors are usually found on 3G/4G/5G devices.

Next, we have the male and female versions of both connector types, and this is where it can get confusing. So, what’s the difference between the SMA male and female connectors? Well, they follow the general rule that the male is a pin end and the female is a pin socket – and as with most things in nature, the male connector goes into the female socket.

Where it can get confusing, is that the female connector housing gets screwed into the male, but if we only concentrate on the pin ends, it follows the standard, male into female. So, the male SMA connector has an inner thread to allow the female to be screwed into it. The female SMA connector has an outer thread, which screws into the male’s inner thread, allowing the male pin to enter and connect with the femal pin socket.

Male SMA connector (notice the pin in the centre and inner thread):

Female SMA connector (notice the pin socket in the centre and outer thread):

OK, so now we know the difference between male and female SMA connectors, what about the difference between male and female RP-SMA (RESMA) connectors?

As we’ve established, the RP-SMA / RESMA connector is a reverse polarity version of the standard SMA connector. Basically, the main difference is that the pins are reversed, so the male has a pin socket and the female has a pin connector.

Male RP-SMA (RESMA) connector (notice the pin socket in the centre and inner thread):

Female RP-SMA (RESMA) connector (notice the pin in the centre and outer thread):

And here’s an image of SMA, RP-SMA male and female compared together:

Hopefully that’s cleared up any confusion over the connector types, with our basic guide to differences and uses of the SMA and RP-SMA (RESMA) connectors.

If you have any further questions relating to any of our connectors and cables or their uses, please get in touch with our technical team on 01449 888000 or email shop@linitx.com.