Connectors - SMA

SMA Connectors

SMA (SubMiniature Version A) connectors are compact threaded coaxial RF connectors widely used for antennas, RF test equipment, wireless equipment, microwave applications, GPS, cellular, Wi-Fi, and other communications systems. The SMA interface uses a 1/4"-36 threaded coupling and normally has a 50-ohm impedance.

One of the advantages of the SMA connector is its excellent RF performance for its relatively small size. Depending upon the particular connector design, cable, and manufacturer specifications, SMA connectors can be used well into the microwave frequency range. Always use the frequency rating of the specific connector or adapter when performance at higher frequencies is important.

Standard SMA and Reverse-Polarity SMA (RP-SMA)

SMA connectors are available in both standard-polarity and reverse-polarity configurations. Reverse-polarity SMA, commonly called RP-SMA, changes the gender of the center contact while retaining the basic threaded interface.

This distinction is especially important with antennas and wireless equipment, where RP-SMA connectors are commonly encountered. Two connectors may look almost identical externally but still have incompatible center contacts. Check both the threaded body and center contact when identifying an SMA or RP-SMA connector.

SMA vs. Type F Connectors

SMA connectors can sometimes be confused with the Type F connectors commonly used for television and cable systems because both use threaded coupling nuts and are relatively small. They are entirely different connector systems and are not interchangeable.

SMA uses a 1/4"-36 threaded RF interface and is normally 50 ohms. Type F connectors are normally associated with 75-ohm television, cable, and related systems and use a different thread and center-contact arrangement. Do not attempt to force the two connector types together.

Selecting an SMA Connector for Your Coax

An SMA connector must also match the coaxial cable on which it will be installed. Cable diameter, center conductor size, dielectric dimensions, shield construction, and connector attachment method all affect compatibility. This becomes especially important with smaller coaxial cables commonly used with SMA connectors.

When selecting an SMA cable connector, verify both the cable type and whether the required interface is standard SMA or RP-SMA.

Common RF Cable Ferrule HEX Crimp Die Sizes*

.429" — LMR-400, RG-8, RG-11, RG-213, RG-214, Belden 8214/9913
.255" — LMR-240, RG-6, RG-8X, RG-59, RG-62, RG-223
.213" — LMR-195/200, RG-58, RG-142, RG-400
.178" — LMR-100/110, RG-174, RG-178, RG-188, RG-196

*The hex crimp sizes shown are nominal sizes. Always verify the required crimp dimensions with the connector manufacturer when the correct size is not known. Connector dimensions can vary between manufacturers and individual connector designs.

The majority of our brand center RF pins are designed to be soldered rather than crimped.