What are BNC connectors?

BNC connectors are miniature radio frequency (RF) connectors developed for low-frequency applications. This quick-connect/disconnect circular connector features a two-stud bayonet-style locking mechanism that users twist and snap into position. A tactile snap indicates a secure connection; a reverse motion disconnects the connector pair.

The BNC connector famously bears the initials of its creators, Paul Neill of Bell Laboratories and Carl Concelman of Amphenol. However, there is some variation in this definition: “B” is generally believed to stand for the bayonet locking mechanism (Bayonet Neill Concelman), although some say it stands for “baby” (Baby Neill Concelman), a reference to the connector’s small size and use with small coaxial cable diameters. Other variations of the name include Baby N Connector, Baby Neill Constant, and British Naval Connector. (Connector Supplier prefers to honor the originators of this important product category and uses “Bayonet Neill Concelman.”)

Neill also developed the N connector and Concelman developed the C connector; together they created the TNC connector — the Threaded Neill Concelman.) Octavio Salati of Hazeltine Electronics Corporation filed the patent for the BNC in 1945 (patent #2,540,012), integrating the bayonet features of the N connector with the slim format of the C connector, and crediting those inventors in the name.

Design Notes

Standardization: CECC 22121, IEC 61169-8, MIL-STD-348B.

Impedance: 50 or 75 ohms

Voltage: Under 500 volts 

Dielectric Withstanding Voltage: 1500 VRMS

Frequency Range: Originally for DC to 1 GHz, today versions are available for 11 and 18 GHz.

Mating Cycles: 500

Temperature Range: -65 ° to 165 °C

Mating Style: Bayonet

Shielding: Twin, or twinax, BNC connectors use the same bayonet latching shell as an ordinary BNC connector but contain two independent contact points (one male and one female), allowing the connection of a 78 ohm or 95 ohm shielded differential pair such as RG-108A. 

Dimensions: The outer diameter of the interface is approx. 0.570 in (14.5 mm); male 0.436 in (11.1 mm), female. Miniature and subminiature versions are available from some suppliers.

Polarity variation: The male connector is typically fitted to a cable and the female connector is affixed to a panel. A variation known as a reverse-polarity BNC (RP-BNC) reverses the polarity of the interface: The female contact normally found in a jack is usually in the plug, while the male contact normally found in a plug is in the jack. This ensures that RP-BNC connectors are not operable with standard interface connectors.

Other options: BNC connectors are available with a wide range of variations and special features, including non-magnetic, hermetically sealed, various plating and housing materials, and flexible and semi-rigid coaxial cable termination styles.

Markets, Sectors, and Applications

Datacom/Telecom, Medical, Military and Aerospace, Test & Measurement, and other markets and applications, including commercial video and radio communications, nuclear instrumentation, and avionics