SMA and RP-SMA connector identification

When working with WiFi router, cellular devices like 4G/5G modems, and handheld radios, you might come across two types of connectors: SMA and RP-SMA. While they look similar, knowing how to tell them apart is crucial to correctly connect your antennas and equipment.

A diagram showing the difference between SMA and RP-SMA connectors

A Brief History

The SMA (SubMiniature version A) connector was developed in the 1960s, and quickly became a standard for connecting antennas to wireless communication devices.

The RP-SMA (Reverse-Polarity SMA) connector was introduced later as a variation of the SMA connector. The original intention behind the development of RP-SMA connectors was regulatory - to prevent the use of unauthorised external antennas that could potentially violate power limits set by regulatory bodies. However, the connectors are now widespread and no longer indicate any particular power level.

SMA Connectors

SMA connectors are more common, and are usually found in 4G/5G technology, handheld radios, and general RF applications. They have a screw-type mechanism and come in two forms - male and female. The SMA male connector features a centre pin and internal threads, whereas the SMA female connector has a centre hole or receptacle and external threads.

RP-SMA Connectors

RP-SMA connectors are typically found in WiFi technology and some LoRaWAN gateways. The key to identifying RP-SMA connectors is understanding the reverse polarity aspect. In RP-SMA, the male connector has a centre hole instead of a pin (opposite to SMA), and the female connector has a centre pin instead of a hole.

Why It Matters

For your devices to function correctly, it's crucial to use the right type of connector. Mixing up SMA and RP-SMA connectors can lead to compatibility issues, as an RP-SMA male and an SMA female connector will physically fit together, but won't establish an electrical connection.

We stock a range of RP-SMA and SMA cables, antennas and adapters:

We also stock a range of coaxial cable assemblies with RP-SMA and SMA connectors, a selection of RF adapters and PCB connectors, and offer a custom cable assembly service. Please get in touch if we can help.


The bottom line: always double-check the centre pin and socket when connecting an antenna to a 4G/5G modem or WiFi access point.