US What an MMCX connector is
An MMCX connector (micro-miniature coaxial) is one of the smallest RF connectors with a positive lock. It was developed in the 1990s as a smaller version of the MCX connector and follows the European CECC 22000 specification. Like other coaxial connectors, it has a centre contact for the signal and an outer body for the shield, and it is normally a 50 ohm part for use with 50 ohm cable.
The coupling is what sets MMCX apart. The plug snaps onto the jack with a detent spring that holds it firmly, but once mated the plug can turn through 360 degrees. That lets a cable or a right-angle plug swing to suit the route without twisting the joint, and it pulls off by hand with no tool or nut to undo.
MMCX is rated from DC to around 6 GHz and for roughly 500 mating cycles, which covers GNSS, Wi-Fi up to 5 GHz bands and cellular frequencies on equipment where space is tight.
MMCX vs MCX, U.FL and SMA
MMCX sits between the tiny press-fit connectors used inside laptops and the larger threaded connectors on antennas. Our explainer on how coaxial cable carries RF signals covers the impedance and loss behind the comparison.
| Connector | Coupling | Typical frequency | Rated mating cycles | Typical use |
|---|---|---|---|---|
| MMCX | Snap-on, rotates 360° | DC to 6 GHz | Around 500 | GNSS and RF modules, camera boards, earphones |
| MCX | Snap-on | DC to 6 GHz | Around 500 | GNSS antennas, older radios, test leads |
| U.FL | Press-fit | DC to 6 GHz | Around 30 | Leads from Wi-Fi and cellular modules to the case |
| SMA | Threaded nut | DC to 18 GHz | Around 500 | External antennas and RF equipment |
The main choice is between MMCX and U.FL for the short lead inside an enclosure. U.FL is smaller and cheaper but only rated for a few dozen connections, so it suits a joint that is made once. MMCX takes repeated connections and holds better under vibration. Both are usually brought out to an SMA or RP-SMA bulkhead on the panel, where the external antenna screws on.
MMCX cables and adapters
An MMCX cable is a short length of thin coax with an MMCX plug on one or both ends. When buying one, check the impedance, the gender and polarity at each end, and the cable type.
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Thin 50 ohm coax. RG178, RG316 and 1.13 mm micro-coax are common. Thinner cable bends more easily but loses more signal per meter, so keep runs short.
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Straight and right-angle plugs. Right-angle plugs suit tight spaces, and the 360 degree rotation lets the cable exit in any direction.
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MMCX to SMA leads. The usual way to bring an internal MMCX port out to a panel-mounted SMA or RP-SMA bulkhead for an external antenna.
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Reverse polarity MMCX. As with RP-SMA, the centre contact genders are swapped. RP-MMCX will not mate with standard MMCX, so match the two.
Where MMCX is used
MMCX turns up wherever an RF connection has to be small, reconnectable and secure against vibration.
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GNSS receivers and modules. Many positioning modules use MMCX for the antenna input. Our explainer on how GNSS differs from GPS covers which constellations a receiver can use.
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Wireless and cellular modules. Some embedded Wi-Fi, LTE and radio boards use MMCX where U.FL would wear out with repeated servicing. Our guide to integrating 4G, LTE and 5G connectivity covers antenna and lead choices for cellular systems.
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Camera and SerDes add-on boards. Some multi-camera boards use locking MMCX connectors to save space. On NVIDIA Jetson carrier boards from Forecr, for example, an eight-channel GMSL2 add-on board takes the cameras on MMCX with power over coax.
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FPV and drones. Video transmitters on drones often use MMCX so the antenna survives crashes and can be swapped quickly.
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In-ear monitors and earphones. Audio makers adopted MMCX for detachable earphone cables because it rotates and swaps easily. These carry audio, not RF, which is why many MMCX cable searches are about headphones.
Fitting and handling MMCX connectors
MMCX joints are reliable when they are fitted and handled the right way, and most failures come from treating them like a threaded connector. Push the plug straight on until it clicks, and pull it straight off by the body, never by the cable or by levering it sideways, which bends the jack’s spring fingers and weakens the retention.
Inside an enclosure, support the cable within a few centimeters of the connector, so vibration is taken by the clamp and not by the joint. Keep bend radii generous on thin coax, because a sharp kink changes the impedance and adds loss. Where a lead will be connected many times during servicing, an MMCX or SMA joint is the better choice than U.FL, and spare leads are worth keeping with the system’s documentation.
Quick answers on MMCX connectors
MMCX connectors: common questions
Is MMCX the same as U.FL?
No. Both are small RF connectors, but U.FL is a press-fit part rated for around 30 connections, while MMCX snaps on, rotates and is rated for around 500. They need an adapter cable to connect.
What is the difference between MCX and MMCX?
Size. MMCX is the smaller of the two. Both snap on and are usually 50 ohm, but they do not mate with each other.
Is MMCX 50 or 75 ohm?
Usually 50 ohm. MMCX is normally a 50 ohm RF connector. Earphone cables use the same shell for audio, where impedance matching does not apply.
Can MMCX connect to SMA?
Yes, with an adapter or lead. MMCX to SMA cables and adapters are common for linking an internal module to an external antenna or test equipment.
Can an MMCX connector rotate?
Yes, through 360 degrees. The snap coupling lets the mated plug turn freely, which relieves strain on the cable and the board.
We fit antennas, RF leads and wireless modules as standard on the systems we build, choosing the internal connectors and the panel bulkheads for each band. Send us your bands, antenna positions and cable runs, and we will specify the leads and connectors to match.