Choosing an RF antenna connector begins with identifying the interface at both ends of the cable. The connector name, such as SMA, RP-SMA, U.FL, TS9, CRC9, or FAKRA, describes only part of the connection. The connector also needs a rear termination that fits the selected coaxial cable, while the cable length, operating frequency, impedance, and installation direction need to suit the complete antenna link. This guide explains where common antenna connectors are used and how to match them with the correct coaxial cable.
Common RF Antenna Connector Types and Where They Are Used
RF antenna connectors can be divided by where they appear in the connection. Small interfaces are usually installed on wireless modules or PCBs. Threaded connectors are commonly used on equipment panels, external cables, and detachable antennas. Other interfaces are designed for specific devices or automotive systems.
U.FL, MMCX, and MCX for Modules and PCBs
U.FL-related miniature connectors are commonly found on WiFi, Bluetooth, GNSS, LTE, and other wireless modules. Their small size allows the RF port to fit on a compact PCB. They are usually connected to thin micro coaxial cables and short internal pigtails.
In this structure, the U.FL end needs to match the exact module port. The other end may be SMA or RP-SMA, depending on the antenna interface. The pigtail also needs enough length for internal routing without leaving excessive cable inside the enclosure.
MMCX and MCX are larger than many board-level micro connectors and may be used when a small detachable connection is needed. Their names and appearances are different from U.FL, so a cable listed as U.FL to SMA cannot replace an MMCX to SMA cable.
SMA and RP-SMA for Compact Equipment and External Antennas
SMA and RP-SMA are common on routers, wireless gateways, communication equipment, antenna pigtails, and detachable antennas. Both use a threaded coupling, but their center contact arrangements are different.
Before choosing the pigtail, confirm whether the device panel uses SMA or RP-SMA and whether the panel connector needs a plug, jack, straight body, or right angle body. A right angle connector also needs the correct cable exit direction.
For a closer comparison of the threaded body and center contact, see our guide to the differences between SMA and RP-SMA.
TNC and N Type for More Robust External Connections
TNC connectors use threaded coupling and are often selected where a more secure connection is needed than a small push-on interface. They can be used on communication equipment, mobile systems, and external antenna cables.
N Type connectors have a larger body and are commonly found on outdoor antennas, communication equipment, base-station installations, and larger coaxial cables. Their size allows them to work with cable structures that are less suitable for small SMA connectors.
For a longer external antenna run, N Type is often paired with a larger low-loss coaxial cable. Confirm that both connector terminations support the selected cable, then compare attenuation at the required frequency and finished length.
TS9 and CRC9 for Cellular Devices
TS9 and CRC9 connectors may be found on cellular routers, modems, hotspots, and compact communication devices. They are often used with a short adapter cable that converts the device port to SMA or another external antenna connector.
A long or heavy cable should not hang directly from a small TS9 or CRC9 port. A short flexible adapter cable can reduce the mechanical load before the connection changes to a larger external cable.
Our guide to TS9 and CRC9 connectors for cellular modules explains device-side interface, cable, and antenna matching in more detail.
FAKRA and Mini FAKRA for Automotive Antenna Links
FAKRA connectors are used in automotive antenna, GNSS, telematics, radio, and other vehicle communication links. Their plastic housings use mechanical coding to reduce incorrect mating.
The housing color helps identify the interface, while the mechanical keying determines whether two housings can mate. Cable type, connector direction, module port, and antenna interface still need to be confirmed separately.
Match the Connector to the Coaxial Cable
The connector interface and the cable termination are two different parts of the same connector. The front interface may be SMA, N Type, TNC, or FAKRA, while the rear structure is designed for a specific cable group.
An SMA plug designed for RG174 is not automatically suitable for RG316 or a generic 1.13 mm micro coaxial cable. The mating end may look identical, but the cable entry, center contact, ferrule, and cable preparation dimensions can be different.
For a cable-specific comparison, review how to match RG174, RG316, and RG58 with RF connectors.
Two cables can both have 50 ohm impedance and still require different connector parts. Impedance describes the electrical characteristic of the cable. It does not define the cable diameter, conductor size, shield thickness, or jacket material.
Choose the Cable by Length and Frequency
Cable choice changes with the length of the antenna connection. A cable that works well for a short internal pigtail may create too much loss when used as a long external feeder.
Short Internal Connections
For a short connection inside an enclosure, cable diameter and flexibility may be the main restrictions. Micro coaxial cable can route between a module port and a panel connector without taking up much space.
The cable should still avoid sharp bends and continuous pulling at the board connector. Additional length should be controlled because unused cable can interfere with other components or place force on the module port.
Flexible Antenna Pigtails
RG174, RG178, RG316, and similar small coaxial cables may be used for flexible pigtails, depending on the required diameter, temperature resistance, shielding, attenuation, and connector availability.
The cable name alone is not enough to make a selection. Decide based on three practical checks: attenuation at the target frequency for the required length, whether the cable diameter matches the connector’s supported range, and whether pre-terminated connector options are actually available for that cable type.
Longer External Feeders
Longer antenna cables generally require more attention to attenuation. A larger low loss cable may be more suitable than a thin pigtail cable, especially as the operating frequency and cable length increase.
Compare attenuation values at the same frequency. A cable specification measured at one frequency cannot be compared directly with another cable specified at a different frequency.
After the cable and connectors are selected, verify the finished assembly across the operating frequency range. Insertion loss shows the total signal loss, while VSWR or return loss checks impedance continuity through both terminations and any adapter transitions.
Adapter, Pigtail, or Direct Cable Assembly
Adapters, pigtails, and complete cable assemblies are not interchangeable solutions. Each structure suits a different connection.
Use an Adapter for a Short Interface Conversion
An adapter can connect two existing interfaces when they are close together and mechanically aligned. It does not add a flexible cable section.
Avoid placing a long or heavy cable directly on a small device port through a rigid adapter. The adapter increases the length of the rigid connection and can place additional force on the port.
Use a Pigtail Between a Small Port and a Larger Connector
A pigtail is suitable when a module uses U.FL, MMCX, TS9, CRC9, or another compact interface, while the external antenna uses SMA, RP-SMA, TNC, or N Type.
The flexible cable allows the larger connector to be fixed to the enclosure or supported separately. This reduces pulling and movement at the small module port.
Use a Complete Cable Assembly for a Defined Connection
A complete cable assembly is suitable when both interfaces, cable type, finished length, and connector direction are already known. It reduces the number of separate adapters and allows the complete RF path to be tested as one assembly.
A direct assembly is especially useful when the connection has mixed interfaces, a fixed routing path, a controlled loss limit, or a right angle connector with a defined orientation.
FAQ
Conclusion
RF antenna connector selection begins with identifying the exact interface at the device end and antenna end. The connector front interface needs to mate correctly, while the rear structure needs to match the selected coaxial cable. Cable length, operating frequency, connector direction, and the number of adapter transitions then determine whether the complete connection is suitable. For a cable assembly with mixed interfaces, special lengths, right angle connectors, or controlled loss requirements, share the two connector interfaces, cable route, and operating frequency with Bafitop so the connector and cable combination can be reviewed before production.