The SMA coaxial connector (or simply SMA) is one of the most common types of coaxial connectors in the RF, microwave, and millimeter-wave (mmW) industries. SMA stands for "SubMiniature version A," and the connector was developed in the 1960s. Interface dimensions and other specifications for SMA connectors are detailed in MIL-STD-348; while originally designed for operation up to 12 GHz, this has evolved, and standard-compliant SMAs can now operate up to 18 GHz without mode limitations. High-precision SMA versions capable of operating up to 26.5 GHz are also available.
SMA connectors are widely used in portable and laboratory test equipment due to their compact size and ease of handling-balancing compactness with reliable operation. Although some SMA connectors are designed for precision assembly using specific housing materials, they can also deliver excellent performance in the field with simple manual tightening.
Since the power-handling capability of a coaxial connector is directly related to its size, SMA connectors are suited for low-to-medium power applications rather than high-power ones. This makes them a popular choice for many telecommunications applications and for low-power interconnections within components. SMAs are frequently used in test and measurement applications operating below 18 GHz because they are ubiquitous, cost-effective compared to other connector standards, and relatively compact. Their widespread use also means a vast array of models and styles is available.
SMA connectors typically offer a mating cycle life of up to 500 connections, though some versions offer greater durability. Like most common coaxial connectors, SMAs generally feature "standard polarity." In this configuration, the connector with internal threads on the housing and a center pin is designated as the "male" connector.
Conversely, the "female" connector features external threads on the housing and an internal socket (receptacle). Reverse-polarity SMA connectors-commonly found in wireless routers and other consumer devices-also utilize center pins and sockets, but the male/female housing configurations are reversed compared to standard-polarity connectors. SMA connectors can be found in a wide variety of coaxial cable form factors, including types designed for cable termination, reusable compression-style board connectors, bulkhead connectors, adapters, and connectors with varying bend radii.