What is an N-type connector? Learn about the N-type coaxial RF connector — its origin, mechanical design, electrical performance, common variants, and applications up to 18 GHz.
Sep 09 ,26
RF Coaxial Connectors: Types Chart & Selection Guide
What Is an RF Coaxial Connector
An RF coaxial connector is a precision electrical component designed to transmit radio frequency signals with minimal loss and reflection between coaxial cables, equipment, and antennas. It maintains the characteristic impedance of the transmission line, typically 50 ohms for communications and 75 ohms for video and broadcast, while shielding signals from external electromagnetic interference.
Choosing the correct RF connector is critical for system performance, signal integrity, mechanical durability, and long-term reliability. A mismatched connector can introduce VSWR problems, power loss, and intermittent connections in the field.
How RF Coaxial Connectors Work
RF coaxial connectors use a center contact and an outer shield contact separated by a dielectric insulator. When mated, the center pins align to carry the signal while the outer conductors form the return circuit and the electromagnetic shield. Precision machining ensures consistent impedance and stable contact resistance across thousands of mating cycles.
- Center contact: carries the RF signal, usually gold or silver plated.
- Dielectric: PTFE or similar low-loss insulator that sets the impedance.
- Outer body: brass or stainless steel shell providing shielding and mechanical strength.
- Coupling mechanism: threaded, bayonet, or push-on style for fast and secure mating.
Main RF Connector Types Chart
The chart below compares the most common RF coaxial connector families used in modern electronics and communications systems.
| Type | Impedance | Frequency Range | Coupling Style | Typical Application |
|---|---|---|---|---|
| SMA | 50 Ω | DC – 18 GHz (up to 26.5 GHz) | Threaded | Wi-Fi, GPS, test equipment, microwave |
| BNC | 50 Ω / 75 Ω | DC – 4 GHz | Bayonet | Lab instruments, video, oscilloscopes |
| TNC | 50 Ω | DC – 11 GHz | Threaded | Vibration-prone, mobile, military radio |
| N-Type | 50 Ω | DC – 11 GHz (up to 18 GHz) | Threaded | Base stations, antennas, radar |
| SMB | 50 Ω | DC – 4 GHz | Snap-on | Telecom boards, quick mating |
| SMC | 50 Ω | DC – 10 GHz | Threaded | Compact RF modules, aerospace |
| MCX | 50 Ω | DC – 6 GHz | Snap-on | GPS, GNSS, small consumer devices |
| F-Type | 75 Ω | DC – 1 GHz | Threaded | Cable TV, satellite, broadband |
| UHF / PL-259 | 50 Ω (non-constant) | DC – 300 MHz | Threaded | CB radio, amateur HF/VHF |
| 2.92 mm (K) | 50 Ω | DC – 40 GHz | Threaded | mmWave test, 5G, radar |
| 2.4 mm | 50 Ω | DC – 50 GHz | Threaded | Lab-grade microwave test |
| 1.85 mm (V) | 50 Ω | DC – 67 GHz | Threaded | High-frequency instrumentation |
Detailed Connector Types
SMA Connector
The SubMiniature version A connector is one of the most widely used RF connectors. With a 50 ohm impedance and excellent performance up to 18 GHz, it is the standard for Wi-Fi modules, GPS antennas, cellular boosters, RF test instruments, and microwave subsystems. SMA connectors use a 1/4-inch hex nut threaded coupling and offer hundreds of reliable mating cycles.
BNC Connector
The Bayonet Neill-Concelman connector is popular in laboratories, broadcast studios, and test equipment because of its quick quarter-turn bayonet locking mechanism. Available in both 50 ohm and 75 ohm versions, BNC connectors operate reliably up to 4 GHz and remain the default on most oscilloscopes and signal generators.
TNC Connector
The Threaded Neill-Concelman connector is essentially a threaded BNC. The screw-on coupling makes it ideal for environments with vibration, shock, or repeated movement, such as mobile radio, military communications, and outdoor antennas operating up to 11 GHz.
N-Type Connector
Designed for heavier cables and higher power applications, the N-Type connector is a threaded, weather-resistant RF connector widely used in cellular base stations, broadcast transmitters, radar systems, and outdoor antenna installations. Its rugged construction supports frequencies up to 11 GHz and beyond.
SMB and SMC Connectors
SMB (Snap-on) and SMC (Screw-on) are miniature 50 ohm connectors designed for internal equipment wiring where space is limited. SMB offers quick push-on mating up to 4 GHz, while SMC provides a threaded version for more secure connections up to 10 GHz. Both are common in telecom PCBs and RF modules.
MCX and MMCX Connectors
MCX and MMCX connectors are micro-miniature 50 ohm designs used where board space and weight matter. MCX provides snap-on mating up to 6 GHz, while MMCX offers a smaller footprint with similar performance. They are standard on GPS receivers, GNSS modules, and compact wireless devices.
F-Type Connector
The F-Type is a 75 ohm screw-on connector that dominates residential broadband, cable television, satellite receivers, and set-top boxes. Low cost and easy installation make it the universal choice for consumer video and DOCSIS modem connections.
Precision Test Connectors: 2.92 mm, 2.4 mm, 1.85 mm
For millimeter-wave and high-frequency test, precision air-dielectric connectors such as 2.92 mm (K), 2.4 mm, and 1.85 mm (V) deliver accurate measurements up to 40 GHz, 50 GHz, and 67 GHz respectively. They are essential in vector network analyzers, RF test racks, and 5G product development.
How to Select the Right RF Connector
Choosing the best RF connector requires balancing electrical performance, mechanical constraints, and environmental conditions. Use the checklist below as a starting point.
- Frequency range: Pick a connector rated comfortably above your maximum operating frequency.
- Impedance match: Match the system impedance — 50 ohms for most RF, 75 ohms for video and broadband.
- Power handling: Verify peak and average power ratings, especially near transmitters.
- VSWR and return loss: Lower VSWR means less reflection and better signal integrity.
- Mating cycles: Test-grade connectors need 500+ cycles; field-installed units usually need far fewer.
- Coupling style: Threaded for vibration, bayonet for speed, snap-on for compact boards.
- Environmental sealing: IP-rated or weatherproof bodies for outdoor or industrial sites.
- Cable compatibility: Confirm the connector matches your cable diameter and center conductor.
- Standards compliance: MIL-STD, IEC, or RoHS where required.
Industry Applications
Telecommunications
SMA, N-Type and 4.3-10 connectors power 4G and 5G base stations, small cells, and DAS networks.
Test & Measurement
BNC, SMA, and precision 2.4 mm/2.92 mm connectors interface with VNAs, spectrum analyzers and oscilloscopes.
Aerospace & Defense
TNC, N-Type and TNC-sealed connectors meet MIL-STD requirements for radar, avionics and tactical radios.
Broadcast & Video
BNC 75 ohm and F-Type connectors carry SDI, HD video, satellite IF and broadband signals.
IoT & Consumer Electronics
MCX, MMCX and U.FL connectors link GNSS, Wi-Fi and Bluetooth modules inside compact devices.
Industrial & Medical
Sealed N-Type and SMA connectors support RFID, MRI coils, and industrial wireless sensors.
Frequently Asked Questions
What is the difference between 50 ohm and 75 ohm RF connectors?
50 ohm connectors are optimized for RF power and data communications, while 75 ohm versions are tuned for video and broadband. They are not interchangeable; mismatched impedance causes signal reflection and degraded performance.
Can SMA and RP-SMA connectors be used together?
No. SMA has a male center pin and female socket; RP-SMA reverses that polarity. They look similar but are mechanically and electrically incompatible. Confirm polarity before ordering antennas and pigtails.
Which RF connector is best for outdoor use?
N-Type with weatherproof sealing and stainless steel hardware is the most common outdoor choice. For low-frequency video, weatherproof F-Type connectors are also widely used.
How many mating cycles can an RF connector handle?
Standard SMA and N-Type connectors are typically rated for 500 mating cycles. Precision test connectors (2.4 mm, 2.92 mm) often reach 500 to 1000 cycles when properly handled.
What does VSWR mean for an RF connector?
VSWR (Voltage Standing Wave Ratio) measures how efficiently RF power is transmitted through the connector. Lower VSWR — closer to 1:1 — indicates better impedance matching and less reflected signal.
Conclusion
Selecting the right RF coaxial connector is foundational to any reliable high-frequency system. By matching impedance, frequency range, mechanical coupling and environmental protection to your application, you maximize signal integrity, reduce maintenance, and extend product life. Use the types chart and selection guide above as a quick reference whenever you evaluate SMA, BNC, N-Type, TNC or precision millimeter-wave connectors for your next design.
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About the Author — MeiXun Team
Wang
Chief Engineer Wang
High-tech Enterprise, Feifeng Talent
Chief Engineer Wang graduated with a master's degree in high-power microwave from the Institute of Electronics, University of Chinese Academy of Sciences.
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