SMA Connector: Everything You Need To Know

SMA Connector

The SMA connector, a semi-precision sub-miniature RF and microwave connector, is widely used, particularly for RF connections inside of electronic systems for frequencies up to 18 GHz and occasionally more.

The SMA connector has a screw-type coupling mechanism that minimizes reflections and attenuation by ensuring uniform contact. It is available in a variety of formats, including male, female, straight, right-angled, bulkhead fitting, and many more.

What Is SMA Connector?

A coaxial cable connector known as a SubMiniature version A (SMA) connector was created in the 1960s as a semi-precision minimal connector interface with a screw-type coupling mechanism. This connector has a coupling mechanism with a 1/4-inch-36 thread size and an impedance of only 50 ohms. It offers excellent performance from 0 to 18 GHz and is usually used as an RF connector for antennas

Sma Connector Performance

The 50-ohm impedance across SMA connectors is intended to be constant. Although some versions have top frequencies of 12.4 GHz, some less, and some are specified up to 24 or 26.5 GHz, the SMA connectors were initially designed and specified for operation up to 18 GHz. It might be necessary for the higher frequency top limits to operate with a greater return loss.

There are various classes of quality and performance, and these factors greatly influence the actual specification for a given connector. It is always best to carefully check the connector specification

In comparison to other connectors used up to 24 GHz, SMA connectors typically have a higher reflection coefficient. This is due to the challenge of precisely securing the dielectric support, but despite this challenge, some manufacturers have successfully solved this issue and can now specify their connectors for operation to 26.5 GHz.

The frequency limit for flexible cables is typically set by the cable rather than the connector. This is due to the small cables that SMA connectors accept, which means that their loss is inevitably much higher than that of the connectors, especially at the frequencies where they are most likely to be used.

SMA Connector

Sma Connector Gender & Mechanical Specifications

SMA Male / Plug Connectors: An SMA Male connector has a barrel with internal threads that encloses the center pin. Plug connectors are another name for SMA Male connectors. They have a hex nut that can be used with a torque wrench to tighten or loosen a connection and have a diameter of 0.312 in (7.9 mm).

SMA Female / Jack Connectors: The center sleeve of an SMA Female connector is encircled by a barrel that has threads on the outside. SMA Female and SMA Jack connectors have similar names. The connector’s thread area measures 6.34 mm in diameter and has an outer thread length of 4.32 mm.

Sma Connector Power Rating

In some circumstances, an SMA connector’s power rating may be crucial. The ability of mated coaxial connectors to pass high currents and maintain a moderate temperature rise is the primary factor that determines the average power handling capabilities of these connectors.

The contact resistance, which is primarily responsible for the heating effect, depends on the contact surface area and how the contacts are mated. The center contacts, for example, are a crucial area that must be well-formed and mate with one another. It should be noted that the average power rating falls with frequency because resistive losses rise with frequency.

SMA connectors can handle 500 watts at 1GHz, dropping to just under 200 watts at 10 GHz, according to some estimates from manufacturers, but this is much more power than many people would feel comfortable passing through them.

Read More: When Would You Typically Use An RJ11 Connector?

Take Away

There are numerous variations of the SMA connector. Both straight and right-angled plug formats are available, and single-pin center solder contacts or cable entries are available for the sockets.

For the purpose of attaching them to a panel, cable entry types typically have a single nut fixing. Additionally, they might be free connectors. The center pin types can be attached to a panel using either a two- or four-screw fixing system.

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