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and network cards, though these have largely been replaced by newer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.
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.