Best Guide to BNC Connectors

Best Guide to BNC Connectors

Summary

BNC RF connectors feature a classic, reliable design that allows them to accommodate a wide variety of RG and industry-standard coaxial cables in a variety of termination styles.

BNC connectors
BNC connectors feature a bayonet-style coupling mechanism for quick connect and disconnect, while also providing positive locking. To mate, simply turn the coupling nut a quarter turn. BNC RF connectors feature a classic, reliable design that allows them to accommodate a wide variety of RG and industry-standard coaxial cables in a variety of termination styles.

1. What is a BNC Connector?

Paul Neill of Bell Labs and Carl Concelman of Amphenol created the Bayonet Neill Concelman (BNC) connector. The original use of BNC connectors was for military applications but are now mainly used in the broadcast market. The connector has evolved to keep pace with the changing industry landscape and now offers the 12G SDI performance required for 4K and Ultra HD applications. The BNC connector type for coaxial cable has been widely adopted and will continue to be a popular choice for current and next-generation video technologies.
 
2. Features and Advantages of BNC Connectors

Customers can match impedance to system requirements using a bayonet coupling mechanism that provides reliable, fast mating. Available in 50 and 75ohm impedance designs.

Military, industrial and commercial connectors are available.
 
Many common BNC coax designs are available.

Female and male BNC configurations
 
3. BNC Connector Application

- Antenna

- Broadcast (75Ω)

- Telecom

- Car

- Computer/LAN

- Medical equipment

- Satellite communications

- Base station

- Cable modem

- Instrumentation

- Military/Aerospace
 
4.75Ohm and 50Ohm

BNC connectors are usually available in 50ohm and 75ohm versions, which are matched to cables with the same characteristic impedance. The 75ohm connector is a slightly different size than the 50ohm variant, but the two can be matched.

- BNC cables and connectors are available in 50ohm and 75ohm sizes.

- The ohm cable/connector is designed for high-quality digital video (CCTV) and can scale its output according to the input.

- 75ohm cables can also be used effectively with older analog video formats, making them more versatile and flexible in any situation.

- When low signal loss is critical, a 75ohm BNC cable/connector can be used.
 
- 50ohm cables and connectors are compatible with older analog video formats. If you're after high-quality video output, 50ohm won't deliver.

- It is possible to connect both types of connectors, but this is not recommended: mixing them will not produce the best output.

- For 50ohm cables, use 50ohm BNC connectors. For 75ohm cables, use 75ohm connectors.
 
5 Application

- 75ohm BNC applications include satellite, HDTV, and cable boxes.

- AM/FM radio receiver.

- Police Scanner. RG-179 coaxial cable has 75ohm BNC connectors for high-temperature environments.

Applications Using RG-179's 75 Ohm BNC Cable

- Use 75ohm BNC connectors on RG-179 coaxial cable.

- Specially designed for high-temperature environments: with TFE tape outer sheath. It can withstand temperatures up to 200 degrees Celsius.

- RG-179 is typically used in high-temperature applications such as:

- Hospital and clinic medical equipment

- Video surveillance cameras are used for security purposes.

- Audio monitoring system.

5.1 50ohm and 75ohm Cables: Differences/Differences

The impedance of 50ohm and 75ohm coaxial cables is measured in ohms, which is a unit of measurement of resistance. The RF signals sent along these cables are alternating current (AC) rather than direct current (DC). The amplitude and phase of the transmitted signal are canceled and contained by the cable as it flows along its length with the AC signal. Therefore, the impedance ratings for coaxial cables are as follows:

Resistance: The amount of resistance to current flow.

The amount of voltage produced by the current magnetic field is called the inductance.

Capacitance is the amount of charge contained or retained in a cable when current flows.

Designed for signal transmission, coaxial cables are constructed to balance resistance, capacitance, and inductance for consistent performance in RF circuits. The impedance of a particular coaxial cable is determined by its composition, including the dielectric constant of the insulation and the radii of the outer and inner conductors.
 
5.2 Why 50ohm and 75ohm?

For most RF applications, using 50 and 75ohms as the standard characteristic impedance for coax is essentially a compromise between optimal power handling and the lowest possible signal loss. These critical impedances were discovered through extensive testing in the early twentieth century. These experiments found that while 30ohm cable provided excellent voltage and power handling, 77ohm coax provided the lowest attenuation.

Therefore, a 50ohm coaxial cable has good power handling and low attenuation. Over the next few decades, 50ohm coaxial cable became the dominant solution for cables with good power handling, especially for cables of 100watts or higher. It is frequently used in antenna cables in amateur and broadcast radio, cellular, and wireless networking applications involving transmitters and transceivers.

For applications requiring low signal loss, low capacitance, and low signal distortion, a 75ohm cable is preferred. It is the coaxial cable of choice for applications requiring low-loss, high-efficiency signal transmission. These cables are often used in applications that require a connection to a receiver, primarily low-power video applications, which do not require the power handling capabilities of a 50ohm cable. Cable TV, HDTV, and CCTV are examples of important applications. 75ohm coaxial cable can also be used for coaxial digital audio, allowing it to carry audio, for example, in a home theater system.

6. Other Types of BNC Connectors

There is also a threaded version of the BNC connector called the TNC connector (Threaded Neil-councilman). This connector has a 50Ω impedance and works best in the frequency range of 0–11GHz. It outperforms BNC connectors at microwave frequencies.

Double BNC or Twinax

Dual BNC (also known as Twinax) connectors have the same bayonet latch housing as regular BNC connectors but have two separate contact points (one male and one female) allowing connection of 78ohm or 95ohm shielded differential pairs, such as RG-108A.

They have a maximum frequency of 100MHz and a voltage of 100 volts. They are not compatible with standard BNC connectors. Twinax connectors are ideal for computer networking applications because they feature keyway polarization to ensure system integrity and prevent signal mixing.

Three-Axis

A Triax connector is a BNC connector that carries signal, protective, and ground conductors. Triax connectors are used in applications requiring maximum RF shielding and minimum noise emissions. These are used in sensitive electronic measurement systems such as Keithley Instruments. Early Triax connectors had only one extra inner conductor, but later Triax connectors use a three-lug arrangement to prevent accidental forcible mating with BNC connectors. Adapters can be used to make some kind of interconnection between triaxial and BNC connectors.

Micro Connector

Mini BNC and High-Density BNC are smaller versions of the BNC connector (HD BNC). While retaining the original electrical specifications, they have a smaller footprint, enabling higher packing densities on circuit boards and device backplanes. Due to their true 75ohm impedance, these connectors are suitable for high-definition video applications. These BNC connectors are widely used in electronics, but in some applications, they are being replaced by LEMO-00 miniature connectors, which allow for higher densities. For higher-density products in the video broadcast industry, use DIN 1.0/2.3 and HD-BNC connectors.

The above introduces some common problems of BNC connectors. If you want to buy BNC connectors, please contact us.

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