SMA vs RP-SMA
When learning about all the parts and pieces that go into building, or upgrading, your WiFi and cellular internet equipment there can be a lot of confusion about what this is and what that is. Today we are going to clarify one of the many subjects that cause confusion for so many people. SMA vs RP-SMA.
Why can't I mix these antennas? What is the difference between a standard WiFi antenna connector and a standard cellular antenna connector? This end doesn't match that end, why?
Right up front we have to state a basic rule that is USUALLY universal:
WiFi antennas and cellular antennas do NOT use the same connectors, so that they do not get mixed up when connecting them to a cellular router.
The general standard is that WiFi antennas use connectors called "RP-SMA" connectors, and cellular antennas use connectors called "SMA" connectors. These two connectors look almost identical, except for one little detail. The only difference between the two is the little pin in the center of the connector.
Nerd Note: SMA stands for "SubMiniature version A" and RP-SMA stands for "Reverse Polarity - SubMiniature version A".¹
If we look at the picture here, you will see that on an SMA connector, the "Male" connector (the hexagonal end that you can spin with a wrench if you wanted to) has a pin in the center of the connector.
The "Female" SMA connector (the threaded connector that is typically on your router or similar device) has a small hole in the center of the connector.
Now notice the RP-SMA Male connector. It is still the hexagonal connector, signifying it is a "Male", but this male end has a hole in its center.
The "Female" RP-SMA is still the threaded connector, signifying it is a female connector, but has the small pin in its center. This is a very small but very important distinction between SMA and RP-SMA.
The naming of each connector end as Male and Female for SMA and RP-SMA seems to refer to the exact same LOOKING connector, but as you can see there is a very small and yet very important difference. The center pin and the center hole.
Hopefully this clarifies for everyone the distinction between SMA and RP-SMA, and when we usually use which one.
Keep building and learning,
-The Wireless Haven
If you need a new set of antennas for your equipment, or are building a router system for yourself, check out the selection of parts we offer in The Wireless Haven store.
There are other, heavier duty, connector types for both WiFi and cellular. For cellular gateway routers, the SMA and RP-SMA are the most common. We stuck with these two for this article.
5.8GHz WiFi antennas tend to use SMA connectors instead of RP-SMA connectors, but not always. Pay attention to the connectors as outlined in this article and you wont get them mixed up.