What is the Function of Copper Braid in Coaxial Cable?

Coaxial cable, often referred to as coax, is a type of electrical cable used primarily for transmitting radio frequency signals. It has a unique design that makes it particularly effective for this purpose, and one of the key components of coaxial cable is the copper braid shield.

At its core, coaxial cable consists of a single conductor that carries the electronic signals that constitute the information being transmitted. This core is typically made of copper or a copper alloy, as copper is an excellent conductor of electricity. Surrounding the core is a layer of dielectric material, which acts as an insulator and separates the core from the outer layers of the cable.

The next layer in coaxial cable is the copper braided shield. This shield is made up of a large number of thin copper wires twisted or braided together to form a continuous layer around the dielectric and core. The primary function of the copper braid shield is to provide a ground connection and to protect the core from electrical noise.

Electrical noise can come from a variety of sources, such as other electrical devices, electromagnetic interference (EMI), and radio frequency interference (RFI). This noise can interfere with the signals being transmitted through the coaxial cable, causing distortion, loss of signal quality, and even complete signal loss. The copper braid shield acts as a barrier between the core and these noise sources, effectively shielding the core from interference.

In addition to providing noise protection, the copper braid shield also helps to maintain the impedance of the coaxial cable. Impedance is a measure of the opposition to the flow of current in an electrical circuit, and it is important for coaxial cable to have a consistent impedance to ensure that signals are transmitted efficiently and accurately. The copper braid shield, in combination with the dielectric layer, helps to maintain the desired impedance level of the cable.

It's worth noting that the copper braid shield must be separated from the core by the dielectric layer to prevent a direct electrical connection between the two. If the core and shield were to touch, it would create a short circuit, and the cable would be unable to transmit signals effectively.

In summary, the copper braid shield in coaxial cable plays a crucial role in protecting the core from electrical noise and maintaining the impedance of the cable. By providing a ground connection and acting as a barrier against interference, the copper braid shield ensures that signals are transmitted efficiently and accurately through the coaxial cable. This makes coaxial cable an excellent choice for transmitting radio frequency signals, such as those used in television, internet, and telephone communications.