Be an RC god | Understanding FPV connectors: SMA vs RP-SMA

This guide will tell you how to quickly tell the difference.

SMA vs RP-SMA Connectors

Historically, the differences were as follows:

● SMA (Sub-Miniature Version A): connectors were developed in the 1960s and it's coaxial RF connectors.

● RP-SMA (Reverse Polarity SMA) is a variation of the SMA connector specification which reverses the gender of the interface.

Antenna connectors used for WiFi devices were SMA and TNC connectors for decades. The problem was that both SMA and TNC were readily available on the market in the form of coaxial cable assemblies and antennas.

To prevent users from equipping their wireless routers with such accessories, the FCC mandated that WiFi manufacturers utilize a new type of connector on the back of their devices, so the manufacturers create an irreplaceable connector.

They simply swapped the center pin and hole location between the male and female connectors. So the term actually refers to this hardware "gender" change.

Illustrating the design difference

From the picture, we can see the differences are in:

● the contact body

● inner pin contact

A male RP-SMA connector has a male contact body and a female inner pin contact. A female RP-SMA is the opposite in both respects-female body (inside threads) with a male inner sleeve contact.

Similarly, a male SMA connector has a male contact body and a male inner hole sleeve contact, and the female SMA is the exact opposite.

The above can be summarized more clearly in the following table:

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