The BNC was named after Paul Neil and Carl Councilman who cooperated in the design. The B stands for „baby“, since it was supposed to be a smaller version of the N-type, and as such was not developed with HF aspects in mind, either. The „B“ may also stand for „bayonet“ - this feature allows for very quick connecting and decoupling.
Just like with the N-connector, the separation point of the inner conductor does not lie within the reference plane. When plug and socked are connected, the clearance is filled with the dielectric which males the impedance dependent on the dielectric, as well. Losses are here accounted for, as well. The construction with interlacing parts enables the connector to have a higher proof voltage than designs with a radial cut point would yield. The bayonet catch does not deliver a sufficient good connection at higher frequencies such that the BNC-type is limited to about 4 GHz..