RF Coax Connector Guide

June 7, 2018 at 8:00 AM


When transmitting radio frequencies over cable, coaxial cables are a perfect fit. With shielding to efficiently carry radio signals, there is a coaxial cable for everything – from cable television to Wi-Fi to industrial and scientific measuring instruments, and every application in between. To maintain the frequency flow and shielding effect, the cables need to be joined by coaxial connectors. These connectors are small but are necessary to transmit signals and they need to match the specifications of the coaxial cable. For your convenience, we’ve compiled a guide to the most popular connector types.




BNC (Bayonet Neill-Concelman) connectors are one of the oldest connector types. They are round with a slotted mating collar and have a bayonet mechanism that is quick-fastening, secure and quick to disconnect. BNC connectors are used with coaxial cable in wireless antenna, television, radio, video, RF electronics and test instrument applications. These connectors are available with 50 or 75 Ohms of impedance. They are usually limited to a frequency of 4 GHz, but that can be increased with higher-quality models.



 Type-N, or N-Type, connectors are the largest RF connectors and are an ideal high-performance option. They are typically used with antennas, communications equipment, power transmitters, receivers and in general RF applications. Type-N connectors are typically rated up to 11 GHz, with higher powered models capable of performance of up to 18 GHz. They have a threaded coupling mechanism and are offered with 50 or 75 Ohm impedance.




TNC (Threaded Neill-Concelman) connectors are similar to BNC connectors except that instead of a slotted mating collar, they are threaded and screw-down to connect. When using BNC connectors, noise is frequently introduced into the transmission signal because if the bayonet fastening. TNC connectors solve that problem by screw-down connector, which allows them to perform better and at higher frequencies than BNC connectors. TNC connectors have an 11 GHz frequency limit and deliver 50 Ohm of impedance. TNC connectors are also available with reversed polarity (RP-TNC) which makes it more difficult to attach high-gain, professional-grade antennas to commercial-grade equipment.





The SMA (Sub-Miniature A) is a much smaller RF connector, approximately half the size of a BNC connector. With a diameter of 6.24 mm-7.9 mm, this connector is ideal for RF connectivity between microwave filters, oscillators, mixers, attenuators and boards. These connectors are rated up to 18 GHz, provide 50 Ohm of impedance and have a threaded coupling for a secure connection. Like RP-TNC connectors, reverse polarity SMA (RP-SMA) connectors were also designed to make it more challenging for consumers to connect larger, more powerful, and potentially illegal, antennas.




Last, but not least on our list, is the SMB (Sub-Miniature B) connector. With a diameter of only 2.2mm-3mm, these are even smaller than SMA connectors, and are small enough to be used with equipment for inter-board or assembly connections. SMB connectors are generally used in GPS, telephone and CATV applications. They use a snap-on fastening system for easy mating and un-mating, are offered with an impedance level of either 50 or 75 Ohm and have a frequency limit of 4 GHz.



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