MCX (micro coaxial connector) 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.

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MCX connectors use a snap-on interface and usually have a 50-Ohm impedance (some are 75-Ohm) . They offer broadband capability from DC to 6 GHz. The contact surfaces are gold-plated.
The outer diameter of the plug is approx 3.6 mm or 0.140 inches.

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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.