IEC 60169-15:1979
Radio-frequency connectors. Part 15: R.F. coaxial connectors with inner diameter of outer conductor 4.13 mm (0.163 in) with screw coupling - Characteristic impedance 50 ohms (Type SMA)
Concerns r.f. coaxial connectors for use with semi-rigid and flexible r.f. cables and specially intended to be used for microwave application requiring high performance. This type of connector is known commercially as the SMA connector.