What is BNC?


The BNC (bayonet Neill-Concelman) connector is a type of RF connector used for terminating coaxial cable. They are (typically pro-video) connections, both for analog and Serial Digital Interface video signals, amateur radio antenna connections, aviation electronics (avionics) and on nearly every piece of electronic test equipment manufactured in the last 35 or so years.


The connector was named after its bayonet mount locking mechanism and its two inventors, Paul Neill of Bell Labs (inventor of the N connector) and Amphenol engineer Carl Concelman (inventor of the C connector), and is much smaller than both the N and the C connectors. Other backronyms the BNC has picked up over the years include: "Baby Neill-Concelman", "Baby N connector", "British Naval Connector", "Bayonet Nut Connector".

BNC connectors were commonly used on 10base2 thin Ethernet networks, both on cable interconnections and network cards, though these have largely been replaced by newer Ethernet devices whose wiring does not use coaxial cable. Some ARCNET networks use BNC terminated coax.


This connector is an alternative to the RCA connector when used for composite video on commercial video devices, however many consumer electronics with RCA jacks can be used with BNC-only commercial video equipment via a simple adaptor.



BNC connectors exist in 50 and 75 ohm versions. Originally all were 50 Ohm and were used with cables of other impedences, the small mismatch being negligible for lower frequencies. The 75 ohm types can be recognized by the reduced or absent dielectric in the mating ends. The different version are designed to mate with each other,[1] although the impedance mismatch will lead to signal reflections. Typically, they are specified for use at frequencies up to 4 and 2 GHz, respectively.

Other Connectors?

A threaded version of the BNC connector, known as the TNC connector (for Threaded Neill-Concelman) is also available. It has superior performance to the BNC connector at microwave frequencies.

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