Coaxial cable

This is a special wire.

It has a wire in the middle. A metal shield wraps around it. A layer of plastic keeps them apart.

This wire carries signals for your TV. It also carries internet to your home. The shield keeps the signal safe inside. It stops other things from getting in the way. This helps the signal stay strong. It is a very useful tool for our world.

A coaxial cable is a special kind of wire.

It is used to carry electrical signals. These signals can be for cable TV or internet. It can also connect radio parts to antennas.

This cable has several parts. First, there is an inner conductor. This is a wire in the center. It is often made of copper. Next, there is a dielectric. This is an insulating material that keeps the parts apart. It can be solid plastic or foam.

Then, there is a shield. This is a metal layer that wraps around the center. It protects the signal from outside interference. Finally, a plastic jacket covers everything to keep it safe.

One big plus of this cable is how it works. The signal stays inside the space between the inner wire and the shield. This means the cable can sit near metal objects without losing power.

A man named Oliver Heaviside helped explain this design. He got a patent for it in 1880. This design helps keep signals strong and clear.

Coaxial cable, often called coax, is a special kind of wire used for many jobs.

It carries high-frequency electrical signals with very low losses. You might see it used for broadband internet or cable television. It also connects radio transmitters and receivers to their antennas. This cable is very important for sending data across computer networks. It is a type of unbalanced transmission line. This means it is a specific way to move electricity from one place to another.

To understand how it works, you should look at its layers. At the very center is an inner conductor. This is usually a wire made of solid or stranded copper.

Surrounding that wire is a dielectric, which is an insulating material. This insulator keeps the center wire at a precise distance from the next layer. The next layer is a conducting shield. This shield is often made of woven metal braid or metallic tape. Finally, a protective outer jacket covers everything to keep it safe.

This design is very smart because of how it handles energy. In an ideal coaxial cable, the electromagnetic field stays inside the cable. This field exists only in the space between the inner conductor and the outer shield. Because the signal stays inside, the cable does not lose much power. You can even install these cables next to metal gutters without problems. It also protects the signal from outside electromagnetic interference. This makes it great for carrying weak signals that might otherwise get lost.

People have been working with these cables for a long time. Coaxial cable was used in the very first transatlantic cable in 1858. Later, an English scientist named Oliver Heaviside explained the theory behind it.

He was a physicist, engineer, and mathematician. He showed how this design could stop interference between parallel cables. He received a British patent for his design in 1880. This patent was known as British patent number 1,407. His work helped make modern communication possible.

There are many different ways to build these cables today. Some use solid plastic for the insulator, while others use foam.

Foam is used because it can contain air or gas. Using air helps reduce losses in the cable. Some high-power cables use a solid copper outer conductor. These cables can be quite large, starting at 0.25 inches in diameter. Other cables use a "quad-shield" with four layers of foil and braid. This extra protection helps keep the signal very strong and clear.

Coaxial cable, or "coax," is a specialized type of electrical transmission line. It is designed to carry high-frequency electrical signals with very low losses. This cable is essential for modern communication systems. It powers broadband internet networking and cable television signals. It also connects radio transmitters and receivers to their antennas.

The term "coaxial" describes its unique geometry. It means the inner conductor and the outer shield share the same central axis. This specific structure allows the cable to function efficiently as a transmission line.

The mechanism of a coaxial cable relies on its layered construction. At the very center is the inner conductor. This is often a solid or stranded copper wire. Sometimes it is silver-plated to reduce losses from the skin effect. The skin effect is a phenomenon where high-frequency current flows mostly on the surface.

Surrounding this wire is the dielectric, which is an insulating material. The dielectric maintains a precise, constant spacing between the inner conductor and the shield. This spacing is vital for maintaining the cable's characteristic impedance. The next layer is the conducting shield. This shield is typically made of woven metallic braid or metallic tape. Finally, a protective outer sheath or jacket covers the entire assembly.

There are many different types of coaxial cables based on their materials. The dielectric can be solid plastic, such as polyethylene (PE) or Teflon (PTFE). Some cables use a foam dielectric, which contains air or gas to reduce signal loss. In fact, foam coax can have about 15% less attenuation than solid versions.

Other designs use air as the insulator, supported by plastic spacers. The shielding also varies. Many cables use a single braided copper shield for flexibility. Some high-performance cables use a "quad-shield," which features four alternating layers of foil and braid. For high-power radio frequency transmission, a solid metal tube may be used instead of a braid.

These solid shields are very effective but cannot be bent sharply without kinking.

The history of this technology is tied to the growth of global communication. Coaxial cable was used in the first transatlantic cable installations in 1858. However, the mathematical theory behind its success was not fully described until much later. An English physicist, engineer, and mathematician named Oliver Heaviside developed the theory.

In 1880, Heaviside received British patent number 1,407 for his design. He demonstrated how the coaxial structure could eliminate signal interference between parallel cables. This discovery was a major step forward for electrical engineering.

Coaxial cables are significant because of how they manage electromagnetic fields. In an ideal cable, the electromagnetic field exists only in the space between the inner and outer conductors. This confinement provides two major advantages. First, it protects the signal from external electromagnetic interference. Second, it prevents the signal from radiating outward.

Because of this, coaxial cables can be installed next to metal objects like gutters. Other transmission lines would suffer power losses if placed near such conductive materials. This makes coax a reliable choice for carrying very weak signals.

Engineers must carefully consider several technical parameters when using coax. One important factor is characteristic impedance, which is determined by the dielectric constant and the radii of the conductors. To ensure maximum power transfer, the source and load impedances must match the cable's impedance. Another factor is attenuation, which is the loss of signal strength as it travels. Attenuation changes based on the frequency of the signal.

Additionally, the cable's voltage handling capability and shield quality are critical for specific applications. Larger diameter cables and those with multiple shields generally offer less leakage.

Coaxial cables connect to other devices using specialized coaxial connectors. These connectors are designed to maintain the same coaxial form and impedance as the cable itself. They are often plated with high-conductivity metals like silver or gold.

Silver is a great conductor, but it can tarnish into silver sulfide, which is poorly conductive. Because of the skin effect, the high-frequency signal actually travels through the plating rather than the connector body. This design ensures that the signal remains strong and clear throughout the entire connection. This precision allows coax to remain a standard in everything from computer data buses to digital audio systems.