Mini BNC 75 Ohm 

Mini BNC 75 ohm RF connector series is a smaller version of the standard BNC.  At around 40% smaller than BNC, the jacks can be mounted on a 14mm pitch, this series is ideal where space is at a premium yet performance can not be compromised.  Suitable for use up to 2Ghz, Mini BNC is used in telecom, broadcast and security markets.  See also our Micro BNC (HD BNC) series for smaller high performance versions of the popular BNC interface.

For details; http://www.coax-connectors.com/products/connectors/bnc-mini.aspx