Table of Contents
A coaxial cable assembly has a simple job: carry RF, video, or high-speed signal energy through a controlled geometry. In a coaxial cable, the center conductor, dielectric, shield, and jacket all work together to maintain characteristic impedance. The connector is the point where that geometry is easiest to disturb.
For buyers, this means the connector type cannot be selected only by shape. BNC, SMA, N-Type, TNC, F-Type, SMB, MCX, MMCX, and FAKRA all solve different mechanical and electrical problems. Some are fast to mate. Some hold up better under vibration. Some are better for sealed outdoor service. Some are compact enough for embedded radios but too delicate for frequent service access.
"The connector launch is where many RF cable assemblies lose margin. Above 1 GHz, a careless strip length or mismatched ferrule can create more practical trouble than the cable type itself."
— Hommer Zhao, Technical Director
The best selection process starts with five questions: required impedance, operating frequency, cable family, environment, and mating cycle expectation. Once those are clear, the connector choice becomes an engineering decision instead of a purchasing shortcut. For complete cable builds, our coaxial cable assembly team checks the connector, cable, strain relief, and test plan as one system.
Coaxial Connector Types Chart
| Connector | Coupling | Impedance | Typical range | Best fit | Watch out for |
|---|---|---|---|---|---|
| BNC | Bayonet | 50 or 75 ohm | Commonly DC to 4 GHz | Test leads, video, lab fixtures, industrial RF | Do not mix 50 ohm and 75 ohm versions without review |
| SMA | Threaded | 50 ohm | Commonly DC to 18 GHz | Wireless modules, antennas, RF instruments | Small threads and contacts need controlled torque |
| N-Type | Threaded | 50 or 75 ohm | Commonly DC to 11 GHz | Outdoor antennas, base stations, higher-power RF | Larger body affects routing and panel spacing |
| TNC | Threaded | 50 ohm | Commonly DC to 11 GHz | Vibration-prone RF, mobile equipment, avionics-style builds | Costs more than BNC but resists accidental disconnects |
| F-Type | Threaded | 75 ohm | Commonly to 1 GHz plus | CATV, broadband, satellite, 75 ohm video paths | Not a default choice for 50 ohm RF systems |
| FAKRA | Keyed plastic latch | 50 ohm | Commonly to 6 GHz | Automotive GPS, cellular, camera, ADAS, telematics | Color and key code must match the vehicle interface |
| MCX/MMCX | Snap-on | 50 or 75 ohm | Commonly DC to 6 GHz | Compact antennas, embedded radios, small instruments | Limited retention force compared with threaded styles |
Frequency ratings vary by manufacturer and exact series, so the numbers above should be treated as common planning ranges, not universal guarantees. A precision SMA built for 18 GHz is not the same as a low-cost board-edge SMA lookalike. A sealed N-Type for outdoor antennas is not the same as an indoor connector on a lab jumper. The manufacturer drawing and cable compatibility table remain the controlling documents.
Connector Family Notes
BNC
BNC is popular because the bayonet coupling is fast and familiar. It works well for test leads, lower-frequency RF, video, and instrumentation. Confirm 50 ohm versus 75 ohm before release.
SMA
SMA is compact and widely used in wireless modules, antennas, and RF test equipment. It rewards careful assembly: torque, pin depth, and dielectric trimming all matter.
N-Type and TNC
These threaded connector families are stronger choices when vibration, outdoor exposure, or higher RF power make bayonet and snap-on styles risky.
FAKRA and mini-FAKRA
FAKRA adds automotive keying and color coding around a coaxial interface. It is common in GPS, cellular, camera, and ADAS cable assemblies.
The BNC connector remains one of the most recognizable coaxial interfaces because it is easy to connect and disconnect without a wrench. That is useful for lab fixtures, service ports, and field test cables. The same convenience can be a weakness in high-vibration equipment, where a threaded TNC or N-Type connector may be the more conservative choice.
SMA connectors are often the default for compact 50 ohm RF assemblies. The SMA connector family is common in antennas, wireless modules, and RF instruments because it can support much higher frequency work than many larger general-purpose connectors. In production, however, SMA is less forgiving than it looks. Over-torque can damage threads and under-torque can create unstable measurements.
Automotive RF programs often move toward FAKRA cable assemblies because color coding, keying, and latch retention reduce assembly mistakes on the vehicle line. For even smaller packaging, our mini-FAKRA cable assembly capability supports multi-channel automotive RF designs where connector density is part of the design requirement.
Assembly and Manufacturing Risks
Coaxial termination is not the same as ordinary wire crimping. The center conductor, dielectric, braid or foil shield, ferrule, and rear strain relief all interact. A small nick in the center conductor can weaken the joint. A braid strand left near the center pin can cause an intermittent short. A ferrule matched to the wrong cable diameter can pass visual inspection but fail pull force or shield continuity later.
Production controls that matter
- Confirm the connector part number is approved for the exact cable OD, dielectric diameter, and shield construction.
- Define strip dimensions for jacket, shield, dielectric, and center conductor in the work instruction.
- Use calibrated crimp dies or solder fixtures matched to the connector series.
- Add bend relief, adhesive heat shrink, booting, or molding when field handling will stress the rear of the connector.
"For volume coax builds, I want the drawing to state the cable family, connector series, strip dimensions, crimp die, and test limit. If one of those 5 items is missing, the supplier has too much room to guess."
— Hommer Zhao, Technical Director
The connector choice also affects strain relief. A small MCX or MMCX termination on RG174 may need a molded boot or controlled routing clip. A large N-Type on LMR-400 may need panel support so cable weight does not load the connector body. For reinforced builds, our overmolding capability can protect the connector transition and improve handling in field-service applications.
Testing Requirements for Coaxial Connectors
Every coaxial assembly should receive basic electrical checks: continuity, shield continuity, and absence of shorts between center conductor and shield. Those tests catch wiring errors, but they do not prove RF performance. For sensitive assemblies, add insertion loss, return loss, VSWR, phase matching, or time-domain reflectometry depending on the application.
The need for RF validation rises with frequency, run length, and system margin. A short internal antenna pigtail may only need continuity and visual inspection if the customer has already validated the design. A base-station jumper, radar lead, or calibrated test cable should define numeric RF limits. Our cable testing process can be adapted to both simple production checks and higher-control RF inspection plans.
"Continuity tells you the connector is wired. VSWR tells you whether the connector transition is behaving like part of a 50 ohm or 75 ohm transmission path. Those are different questions."
— Hommer Zhao, Technical Director
Basic production
Continuity, shorts, shield continuity, visual inspection, label verification, and pull checks where required.
RF validation
Insertion loss, return loss, VSWR, phase, and impedance checks for frequency-sensitive assemblies.
Environmental checks
Seal inspection, bend relief review, vibration planning, and IP67 or IP68 strategy for outdoor builds.
RFQ Checklist Before You Freeze the Connector
A strong RFQ prevents substitutions that look harmless on a BOM but change the finished cable. Include the connector manufacturer and full part number, cable specification, impedance, length tolerance, bend radius requirement, labeling method, environmental target, mating-cycle expectation, and test requirement. If the connector is customer-supplied, include the mating interface and panel geometry so the cable assembly supplier can check clearance.
Minimum data to send
- Connector family and exact part number
- 50 ohm or 75 ohm impedance requirement
- Cable type, OD, shield, jacket, and temperature rating
- Finished length and tolerance
- Indoor, outdoor, sealed, or overmolded service
- Continuity-only or RF test limits
- Labeling, serialization, and packaging needs
- Prototype quantity and expected annual volume
Coaxial Connector Types FAQ
What are the most common coaxial connector types for cable assemblies?
The most common coaxial connector types are BNC, SMA, SMB, MCX, MMCX, N-Type, TNC, F-Type, UHF, and FAKRA. In production cable assemblies, the right choice depends on impedance, frequency, mating cycle target, cable diameter, and whether the assembly needs 50 ohm or 75 ohm performance.
Which coaxial connector type is best for 50 ohm RF cables?
SMA, N-Type, TNC, BNC, SMB, MCX, MMCX, and many FAKRA connectors are commonly used in 50 ohm RF cable assemblies. SMA is often selected for compact test and wireless applications up to 18 GHz, while N-Type and TNC are stronger choices for outdoor or higher-power RF links.
Can BNC connectors be 50 ohm and 75 ohm?
Yes. BNC connectors are available in both 50 ohm and 75 ohm versions, and mixing them can create return-loss problems. For video, broadcast, or instrumentation programs, the drawing should state 50 ohm or 75 ohm explicitly and match the cable type, connector body, and test requirement.
What coaxial connector is best for waterproof cable assemblies?
N-Type, TNC, sealed FAKRA, and some industrial BNC variants are common choices for waterproof coaxial cable assemblies. A connector alone does not guarantee sealing; production usually needs the correct gasket, rear boot, adhesive heat shrink, or overmolded strain relief to target IP67 or IP68 performance.
How many mating cycles do coaxial connectors support?
Typical commercial RF connectors are often rated from about 100 to 500 mating cycles, depending on family, plating, coupling style, and manufacturer. Test leads that are mated daily need a higher-cycle connector strategy than an internal antenna cable that is installed once.
Do coaxial connector types affect VSWR and insertion loss?
Yes. Connector geometry, cable strip length, shield termination, and contact alignment all affect VSWR and insertion loss. For RF cable assemblies above 1 GHz, even a small mismatch at the connector launch can matter, so production should define return-loss or VSWR testing when signal margin is tight.