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What is a coaxial cable and how does it work?

Headshot of Dave Schafer
Researched by
Dave SchaferContributing Writer
Headshot of Bri Field
Reviewed by
Bri FieldAssigning Editor
Updated 3/24/23

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Coaxial cables, often referred to as “coax” cables, are a type of copper cable used primarily in TV, internet, and phone services. They carry data transmissions from one point to another.

These cables have been used widely since the late 1800s and remain one of the most common types of cable used in data transfer, although fiber optic cables are slowly catching up as the preferred option.

In this article, we’ll explore how coaxial cables work and how they’re used to bring you speedy internet and clear TV pictures all over the country.

How do coaxial cables work?

Coaxial cables are made up of a core, an insulator, a shield, and a jacket. The core is usually a single copper wire and performs the main function of the cable—to carry the signal. The insulator is often made of polyethylene and helps provide protection to the copper wire core. The shield is often made of copper as well and helps reduce electromagnetic interference. Since it’s copper, it also helps carry the signal. Finally, the jacket is typically a hard plastic material that protects everything inside.

Coaxial cables work by transmitting signals down both the center wire and the metal shield at the same time. The insulator prevents the two signals from coming in contact with each other—if they did, they would cancel each other out and render the cable useless.

The end result is a cable that can be carried over very long distances with minimal signal loss. This makes coaxial cables ideal for transmitting cable TV and cable internet signals, which is what they’re most often used for today.

Are there different types of coaxial cables?

There are a few different designations for coax cables. The most common ones are in the RG series. RG stands for Radio Guide. These are the original military specifications for coax cables and indicate the cable’s specifications. The RG-series of cables includes:

  • RG-6/U: These cables have an impedance of 75 Ohm and are commonly used for cable TV and other residential and commercial applications. Impedance, measured in Ohms, indicates the electrical resistance of a cable, which can impact data transfer rates.
  • RG-8: These cables are similar to the RG-6, but can’t carry pure video signals. They have an impedance of 50 Ohm and are typically used for audio applications, such as in radio stations and audio control rooms.
  • RG-11: RG-11 cables have an impedance of 75 Ohm, but a higher gauge (thickness) than RG-6. These are used for video distribution, such as HD TV.

Generally, if you’re buying a cable to use for your home TV service, you want to go with the RG-11 option—it’s ideal for carrying video signals.

There are some newer coaxial cable types as well, including the LMR coax cables. However, these are still less common and you’re less likely to run into them when dealing with your home internet or television service. They’re often used on missiles, satellites, and airplanes.

Does the length of a coaxial cable matter?

Yes, the length of your cable matters. If you’re shopping for a coax cable—say, to connect your DVR or TV to a cable jack in your home—you want the shortest cable you can get away with. While coax cables are very good at transporting information, some data is inevitably lost in the process. The longer the cable, the more likely this is to happen.

Old tech that's still going strong

Coaxial cables have been around for a while. Although fiber has tried to take their place, they’re still going strong. Whether it’s for TV and internet service or a special wiring job, coax cables offer a time-tested design that can handle a good amount of bandwidth for a reasonable price.

Looking for cable internet? Check out our roundup of the best cable internet providers.

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Contributing researcher
Headshot of Dave Schafer
Researched by
Dave SchaferContributing Writer

Dave Schafer is a freelance writer with a passion for making technical concepts easy for anyone to understand. He’s been covering the world of gadgets, tech, and the internet for over 8 years, with a particular focus on TV and internet service providers. When he’s not writing, Dave can be found playing guitar or camping with his family and golden retriever, Rosie.

Contributing reviewer
Headshot of Bri Field
Reviewed by
Bri FieldAssigning Editor

Bri Field has a background in academia, research writing, and brand marketing. She has edited scientific publications, conference papers, digital content, and technical communications. As Assigning Editor, she enjoys ensuring all content is accurate, clear, and helpful. In her free time, you can find her in the kitchen trying a new recipe, out on a hike, or working through her massive TBR list.