page_title: SMA connector
section_title: Variations
hierarchical_section_title: SMA connector / Variations
caption_attribution_description: English: Picture of SMA, 3.5 mm and 2.92 mm coaxial connectors
context_page_description: SMA connectors are semi-precision coaxial RF connectors developed in the 1960s as a minimal connector interface for coaxial cable with a screw-type coupling mechanism. The connector has a 50 Ω impedance. SMA is designed for use from DC to 18 GHz, and is most commonly used in microwave systems, hand-held radio and mobile telephone antennas, and more recently with WiFi antenna systems and USB software-defined radio dongles. It is also commonly used in radio astronomy, particularly at higher frequencies.
  SMA connectors must not be confused with the standard household 75-ohm type F coax connector, as there is only about a 2 mm difference overall in the specifications. Type F cannot be mated with SMA connectors without the use of an adapter.
  The SMA name is also used for a superficially similar optical fiber connector.
context_section_description: The SMA connector is typically rated for mode-free operation from DC to 18 GHz, though some proprietary versions are rated to 26.5 GHz . For performance above this, other SMA-like connectors are used. These include the 3.5 mm connector, rated to 34 GHz, and the 2.92 mm (also known as 2.9 mm, K type, or SMK), good up to 46 GHz. These connectors keep the same outside thread as the SMA, so they can potentially be cross-mated, but the precision connector can be easily damaged when mating with low-grade SMA connectors. The precision versions use an air dielectric with appropriately scaled center conductors.
  Beyond 46 GHz, the 2.4 mm, 1.85 mm (also known as V type) and 1.0 mm (also known as W type) connectors exist. These are similar to the SMA connector, but with the geometries incompatibly scaled, and a metric thread to prevent accidental intermating. (But 2.4 mm and 1.85 mm connectors are compatible to each other.) These offer  mode-free operation to 50, 65, and 110 GHz respectively.
caption: Picture of SMA (left), 3.5 mm (center) and 2.92 mm (right) coaxial connectors. Top: male versions, bottom: female versions. The air-dielectric is clearly visible in the 3.5 mm and 2.92 mm versions
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