What is a BNC Cable And What does BNC Stand for?

BNC Cable Assembly

A common type of coaxial cable assembly used throughout the RF industry is a BNC cable, or BNC coaxial cable assembly. A BNC cable is used for signal routing below roughly 4 GHz (there are high precision BNC connectors that reach maximum frequencies to 12 GHz or beyond). BNC stands for Bayonet Neill–Concelman, and is a miniature quick connect/disconnect style RF coaxial connector. A BNC cable is a coaxial cable that has BNC connectors on either end. This type of cable is used to route signals from test equipment or devices that have BNC coaxial connector ports, where the ports are typically RF female connectors, and the BNC connectors are RF male connectors. Though, there are BNC connectors with reverse polarity, or reverse polarity BNC (RP-BNC).

These connector and cable styles are used as mating between a male and female connector is done by inserting the RF male connector into the female port  using the alignment guides (lugs) and applying a relatively small amount of force to turn the male connector bayonet structure a quarter turn. Given the wide use of BNC cables, these cables also often come with a single BNC connector side and the other coaxial side in a different connector type or interface, such as 10-32, alligator, banana, BNC, FME, GR874, hook, mini alligator, mini banana, MMCX, N, NMO Mount, SMA, SMB, SMC, Tip, TNC, UHF or unterminated leads used for direct soldering, clamping, etc. These cables are typically made in either 50-ohm varieties or 75-ohm varieties. The nominal impedance of these cables depends on the application, where broadcast, audio/visual, and low frequency communications may use 75 ohms, most RF applications use 50 ohms. BNC cable assemblies were also used widely in early computer and electronics networking equipment and also for a range of analog/digital interfacing and signal routing.

Key Takeaways 

• “BNC” stands for Bayonet Neill-Concelman, referring to the quick-connect bayonet lock design and its inventors. 

• A BNC cable is a coaxial cable terminated with BNC connectors. They are commonly used for RF signal routing, test equipment, video systems, and data links.  

• BNC connectors exist in both 50 Ω and 75 Ω versions; 50 Ω is typical for RF/data, while 75 Ω is common in broadcast/video.  

• The standard frequency range for BNC connectors is up to ~4 GHz for many models, with precision variants rated higher (10-12 GHz+). 

• The bayonet coupling (quarter-turn lock) makes BNC connectors fast to mate/un-mate while maintaining consistent impedance and minimal signal disruption.  

Both 75 ohm and 50 ohm BNC cables can mate non-destructively per the 2007 IEC standard, IEC 61169-8. This type of mating is only recommended for very low frequencies ( < 10 MHz) as the impact of the impedance mismatch at higher frequencies becomes more significant as a function of frequency. BNC cables are generally only used for signal applications and are generally note rated for high voltages or high-power use. However, there are high voltage BNC (HV-BNC) and high-power BNC connector variants available that can be installed on appropriate high voltage and high-power coaxial cable.

FAQs (Frequently Asked Questions) 

Q1. What does BNC stand for?
A: BNC stands for Bayonet Neill–Concelman, named after its inventors and the bayonet-style connection system. 

Q2. What is a BNC cable used for?
A: BNC cables are used for transmitting RF, video, and data signals in applications like CCTV systems, oscilloscopes, antennas, and test equipment. 

Q3. What is the difference between 50 Ω and 75 Ω BNC connectors?
A: 50 Ω BNCs are ideal for RF and data communications, while 75 Ω versions are designed for video and broadcast systems to minimize signal loss. 

Q4. Are BNC connectors compatible with SMA or N-type connectors?
A: Not directly. However, Pasternack provides BNC-to-SMA and BNC-to-N adapters to allow interoperability across connector types. 

Q5. How do I know if my BNC connector is 50 Ω or 75 Ω?
A: Check the manufacturer’s marking or use calipers  75 Ω BNCs have a thinner dielectric and smaller center pin than 50 Ω types.