MCX (micro coaxial) connectors are coaxial RF connectors developed in the 1980s. They have the same inner contact and insulator dimensions as the SMB connector but are 30% smaller. MCX is standardized in European CECC 22220. They use a snap-on interface and usually have a 50 Ω impedance (occasionally 75 Ω also) . They offer broadband capability from DC to 6 GHz.[2] The contact surfaces are gold-plated.

This type of connector is used on the Apple Airport Extreme Base Station's external antenna port and requires an adapter for most antennas. MCX and the smaller MMCX connector are frequently used to connect external antennas to GPS receivers. They are also common on USB DVB-T tuners for computers and laptops, to connect an external antenna to the tuner.

The outer diameter of the plug is approx 3.6 mm or 0.140 inch.

MMCX (micro-miniature coaxial) connectors are coaxial RF connectors similar to MCX but smaller. They conform to the European CECC 22 000 specification. The connectors have a lock-snap mechanism allowing 360-degree rotation and usually have a 50 Ω impedance. They offer broadband capability from DC to 6 GHz.[1]

MMCX connectors are most commonly seen on Wi-Fi PCMCIA cards as antenna connectors or as connectors for external GPS antennas on small devices like PDAs or GPS receivers. They were developed in the 1990s.