What Are the Common Coaxial Connectors?

Coaxial connectors are the most fundamental and critical interface components in RF and microwave systems, primarily used to ensure reliable connections between signal lines, shielding layers, and receiving devices. As illustrated in the table, commonly used coaxial connectors include BNC, TNC, SMA, SMB, SMC, MCX, BMA, and N types. They differ significantly in terms of structural design, mating method, maximum operating frequency, impedance characteristics, and primary applications, making them suitable for different communication environments and equipment requirements.

(1) BNC Connector (Bayonet Nut Connector)
The BNC connector features a bayonet-style structure, making it easy to use. Its typical operating frequency is below 4 GHz and it is widely employed in instruments, computer networks, and monitoring equipment for medium-frequency or moderate-bandwidth applications. With a simple structure and high cost-effectiveness, it is one of the most common standard interfaces in the testing field.

(2) TNC Connector
The TNC connector uses a threaded coupling method, offering better mechanical stability and vibration resistance compared to the BNC. Its maximum operating frequency can reach 11 GHz, making it suitable for applications with strong mechanical vibrations, such as aerospace, mobile communications, and radar. With a size similar to BNC, it can be considered a higher-performance alternative.

(3) SMA Connector
SMA connectors are among the most widely used microwave connectors, characterized by high precision and excellent impedance matching, making them a key interface in RF chains. When paired with flexible cables, they operate up to 12.4 GHz; with semi-rigid cables, up to 26.5 GHz, supporting both 50Ω and 75Ω impedances. They are extensively used in communication equipment, radar modules, RF front-end systems, and also have miniaturized versions such as SSMA.

(4) SMB Connector
SMB connectors feature a snap-on locking design, offering quick mating and compact size. A 50Ω SMB operates up to 4 GHz, while a 75Ω SMB operates up to around 2 GHz. They are commonly used in digital communications, portable devices, and RF links requiring high-speed connections, serving as a smaller alternative to SMA/L9 interfaces, with even smaller variants like SSMB available.

(5) SMC Connector
SMC connectors use a threaded coupling mechanism, with a compact structure supporting a wide frequency range. They are suitable for high-vibration environments and applications requiring both small size and strength. Miniature versions such as SSMC are also available.

(6) MCX Connector
MCX connectors feature a snap-on design with a smaller footprint and a typical operating frequency below 6 GHz. They are commonly used in RF modules, communication terminals, and compact consumer electronic devices. Micro versions such as MMCX also exist.

(7) BMA Connector
BMA connectors are high-performance interfaces with a maximum operating frequency of up to 18 GHz. They are commonly used for blind-mate connections in low-power microwave systems, suitable for modular equipment inside enclosures.

(8) N-Type Connector
N-type connectors are larger in size but highly reliable, with a maximum operating frequency of around 11 GHz. They are widely used in test instruments, base station equipment, and power transmission links, and remain an important standard interface in aerospace and outdoor equipment.

In general, large connectors such as N and TNC emphasize power handling and mechanical reliability; medium-sized connectors like SMA balance frequency performance with electrical reliability; and small connectors such as SMB, MCX, and MMCX are suitable for high-density, compact, and easily mated applications. Engineering selection should consider factors such as bandwidth, power, installation space, and vibration conditions.

About Kinghelm
Kinghelm is a high-tech enterprise specializing in RF and connectivity solutions. The company offers a wide range of products, including Beidou/GPS antennas, Wi-Fi, Bluetooth, NB-IoT, LORA, Zigbee antennas, RF cables and connectors, board-to-board and plug-in connectors, switches, terminals, and customized automotive and industrial components. With over 17 years of experience, Kinghelm serves industries such as automotive, telecommunications, industrial automation, medical devices, and consumer electronics. Known for durable, reliable components that meet international standards, Kinghelm supports applications ranging from renewable energy to IoT devices.