What is the difference between SMA and BNC connectors?

SMA is a threaded 50 Ω connector operating up to 18 GHz — the RF workhorse. BNC uses a quick-connect bayonet, tops out at 4 GHz, and is standard on test equipment and legacy video networks. SMA is preferred for vibration; BNC for fast connect/disconnect.

What frequency does Type N support?

Type N connectors operate up to 11 GHz at 50 Ω with rugged threaded coupling. They are used for cellular base stations, broadcast, and microwave links where higher power and lower VSWR than SMA are required.

What is the difference between 50 Ω and 75 Ω coaxial connectors?

50 Ω is optimized for RF power and low loss in test, telecom, and microwave links. 75 Ω is standard for video, cable TV, and satellite IF — it minimizes loss over long cable runs but does not work for power transmission.

Can SMA connectors be used above 18 GHz?

Standard SMA is rated to 18 GHz, but precision SMA (3.5 mm / 2.92 mm) versions reach 26.5 GHz and 40 GHz respectively. These are test-grade versions with tighter tolerances and higher cost.

What is MCX used for?

MCX (and the smaller MMCX) are 50 Ω micro-miniature snap-on coaxial connectors for dense PCB layouts. They are common in GPS modules, IoT devices, and consumer Wi-Fi where space is at a premium and a few mating cycles suffice.

Connector Basics

RF Coaxial Connector Guide: SMA, BNC, Type N, MCX, and More

September 2, 2026 4 min read

Tags:

#50 ohm connector #BNC connector #RF coaxial connector #SMA connector #Type N connector

An RF connector is part of the transmission line. Even when two interfaces mate mechanically, the wrong impedance, launch geometry, cable, assembly method, or frequency grade can create reflections and loss. Select the connector and cable assembly together, using measured performance over the actual operating band.

Quick Reference

Connector	Impedance	Frequency	Size	Common Use
BNC	50/75Ω	up to 4 GHz	Medium	Test equipment, video, instrumentation
TNC	50Ω	up to 11 GHz	Medium	Wireless, RF systems
SMA	50Ω	up to 18 GHz	Small	Antennas, modules, test
SMB	50Ω	up to 4 GHz	Small	PCB connections, compact
SMC	50Ω	up to 10 GHz	Small	Military, telecom
N	50Ω	up to 11 GHz	Large	Base stations, high power
MCX	50Ω	up to 6 GHz	Micro	GPS, Wi-Fi, compact
MMCX	50Ω	up to 6 GHz	Micro	GPS, small modules
U.FL / IPEX	50Ω	up to 6 GHz	Ultra-micro	Wi-Fi, Bluetooth modules

1. What Is a Coaxial Connector?

An RF coaxial connector maintains a controlled 50Ω (or 75Ω) impedance through the connection. It has:
– Center pin (signal)
– Dielectric insulator (maintains spacing = impedance)
– Outer shield (ground, also provides mechanical coupling)

The connector’s impedance must match the cable and equipment — any mismatch causes signal reflection, reducing the RF performance.

2. SMA: The Workhorse (Up to 18 GHz)

SMA (SubMiniature version A) is the most common RF connector for modules, antennas, and test equipment.

Parameter	Specification
Impedance	50Ω
Frequency	DC–18 GHz (some to 27 GHz)
Coupling	Threaded (1/4-36 UNF)
VSWR	<1.05 (typical)
Mating cycles	500+
Size	4.1mm hex nut

SMA Types

Type	Use
SMA male (plug)	Cable end, threaded pin
SMA female (jack)	Equipment end, threaded socket
RP-SMA (reverse polarity)	Wi-Fi antennas — reversed gender

RP-SMA is critical for Wi-Fi: FCC regulations require non-standard connectors on consumer Wi-Fi antennas. RP-SMA male has a socket in the center (reversed).

3. BNC: The Test Standard (Up to 4 GHz)

BNC (Bayonet Neill-Concelman) uses a bayonet coupling — push and twist to lock. Fast connect/disconnect, common in test equipment.

Parameter	Specification
Impedance	50Ω or 75Ω (version-dependent)
Frequency	DC–4 GHz
Coupling	Bayonet (push-twist)
Speed	Fastest connect of any RF connector

75Ω BNC is used in video (composite, SDI). 50Ω BNC is used in RF test and instrumentation. Because the interfaces can appear similar, verify impedance before mating; mixing them introduces mismatch and may damage precision contacts.

4. N: The High-Power Standard (Up to 11 GHz)

N (Type N) connector handles higher power and provides better weather sealing than SMA.

Parameter	Specification
Impedance	50Ω
Frequency	DC–11 GHz
Coupling	Threaded (5/8-24 UNEF)
Power handling	Up to 1000W (at low frequency)
Sealing	Weatherproof versions available
Use	Base stations, antennas, high-power RF

5. PCB-Mount Coaxial Connectors

Connector	PCB Mount	Frequency	Use
SMA (edge mount)	Edge launch	18 GHz	Module I/O
SMB (snap-on)	Through-hole/SMT	4 GHz	Compact, quick connect
MCX	Through-hole/SMT	6 GHz	GPS, cellular modules
MMCX	Through-hole/SMT	6 GHz	Small modules, radio
U.FL/IPEX	SMT	6 GHz	Wi-Fi, Bluetooth

6. VSWR and Insertion Loss: What to Check

Parameter	Definition	Good Value
VSWR	Voltage Standing Wave Ratio (reflection)	<1.2
Insertion loss	Signal loss through connector	<0.1 dB
Return loss	How much signal reflects back	>20 dB

A poorly matched connector reflects signal, which degrades the RF link. Always specify connectors matched to your cable and system impedance (50Ω vs 75Ω).

7. Selection Checklist

Specify impedance, operating-frequency range, maximum power, cable type, PCB or bulkhead launch, coupling method, environmental sealing, mating cycles, plating, VSWR/return-loss target, and insertion-loss budget. For PCB launches above several gigahertz, request the recommended land pattern and validate the complete transition with the actual board stack-up.

8. GSConn RF Coaxial Series

Series	Type	Frequency	Features
RF-SMA	SMA male/female, RP-SMA	18 GHz	Threaded, gold center pin
RF-BNC	BNC 50Ω/75Ω	4 GHz	Bayonet, fast connect
RF-N	Type N	11 GHz	High power, weatherproof
RF-MCX	MCX	6 GHz	Compact PCB mount
RF-UFL	U.FL/IPEX	6 GHz	Ultra-micro, Wi-Fi modules

GSConn RF coaxial connectors cover SMA (including RP-SMA), BNC, N, MCX, and U.FL series in 50Ω and 75Ω. Gold-plated center pins, PTFE dielectric, and PCB-mount options. VSWR and insertion loss data available for all series.