The interface specifications for the BNC and many patch cable vs vga connectors are referenced in MIL-STD-348. Similar connectors using the bayonet connection principle exist, and a threaded connector is also available.
The BNC was originally designed for military use and has gained wide acceptance in video and RF applications to 2 GHz. The BNC uses a slotted outer conductor and some plastic dielectric on each gender connector. This dielectric causes increasing losses at higher frequencies. Above 4 GHz, the slots may radiate signals, so the connector is usable, but not necessarily stable up to about 11 GHz. Both 50 ohm and 75 ohm versions are available. The BNC connector is used for composite video on commercial video devices.
Consumer electronics devices with RCA connector jacks can be used with BNC-only commercial video equipment by inserting an adapter. Typically the male connector is fitted to a cable, and the female to a panel on equipment. Cable connectors are often designed to be fitted by crimping using a special power or manual tool. The basis for the development of the BNC connector was largely the work of Octavio M.
Salati, a graduate of the Moore School of Electrical Engineering of the University of Pennsylvania. The patent was granted in 1951. From left to right: 75 Ω female, 75 Ω male, 50 Ω female, 50 Ω male. BNC connectors are most commonly made in 50 and 75 ohm versions, matched for use with cables of the same characteristic impedance. The 75 ohm types can sometimes be recognized by the reduced or absent dielectric in the mating ends but this is by no means reliable. DS3 Telco central office applications primarily use 75 ohm BNC connectors, whereas 50 ohm connectors are used for data and RF.