What Are Coaxial Cables?

Coaxial cable is a data transmission line that has existed since the early 20th century, giving rise to long-distance phone calls, radio, television, and, eventually, the internet. Its design gives it the ability to transmit high-frequency radio signals with little interference. Even with its limitations compared to more modern cable technologies, coax is a versatile shielded cable for the transmission of audio, video, and data. 

Explore what a coaxial cable is, the elements that make up its design, types, applications, and alternatives to coaxial cable. 

What are coaxial cables?

Coaxial cable or coax is a type of cable family that transmits video, audio, and data; it uses a singular center conduction and outer shield on the same axis. The “signal” that coax cable transmits is a high-frequency radio signal through its copper center. While coax cable is an important cabling solution for networks, especially at homes, it has disadvantages in distance, losing signal at long lengths. At the same time, newer technology like fiber optics carries signals much faster and farther.

Let’s take a closer look at the elements that make coaxial cable unique and the situations in which it provides the most advantages. 

Read more: Information Technology (IT) Terms: A to Z Glossary

Elements of coaxial cable

Coaxial cable uses various elements that make it unique and perform its specific function. Most coax cables contain these basic elements:

• Center conductor: A single or stranded copper or copper-coated wire at the core of the cable where the signal transmits through 

• Dielectric insulator: A polyethylene plastic that wraps the center conductor, giving it stability and spacing between the shield 

• First outer conductor or foil shield: An aluminum-polymer-aluminum tape attached around the dielectric that is fairly common in most coax cables 

• Second outer conductor or braided shield: A 34 or 36 AWG aluminum or copper braid that is on the same axis as the center conductor, shielding the signal from interference 

• Outer jacket: An ultraviolet (UV) light-stable plastic used to hold the inner elements together and protect them from outside factors

These are the most basic elements of a functioning coax cable. Some cables may be thicker and have additional outer conductors to protect the signal flow or additional components to protect the center conductor from moisture. 

Coaxial cable sizes and specifications

Coaxial cables use radio grade (RG) for sizing and specifications depending on their best-use scenario. These kinds of coax cables carry radio frequency signals and have specific use cases based on the cable length needed for the network. For example, RG-6 cable is a thinner cable that can carry higher frequencies over longer distances and is commonly used for commercial and home cabling solutions, including cable or satellite television and internet. RG-59 is better over shorter distances for low-frequency uses, such as audio video (A/V), security cameras, and closed-circuit television (CCTV).

Other factors that lead to the further specification of coax cables include:

• Center conductor material

• The impedance of the coaxial cable

• The jacket material

• Dimensions, such as length, gauge of wire, and diameter

Connectors

Coax cables use different connectors, the most common being the Bayonet Neill-Concelman (BNC) connector. This connector provides the simplest connection by plugging in the cable and doing a quarter turn that locks it in place. The Threaded Neill-Concelman (TNC) is similar to the BNC, except it must be fully twisted in. Other connectors include the Subminiature Version A (SMA), 7/16 DIN, and QMA, all of which have different properties depending on the cable type being run. 

Read more: What Is A Patch Panel?

Types of coaxial cable

A variety of cables exist to meet specific needs. Below is a list of common cable types:

• Flexible coaxial cable

• Hardline coaxial cable

• Semi-rigid coaxial cable

• Formable coaxial cable

• Rigid coaxial cable

• Twinaxial cable

• Triaxial cable

Take a closer look at the differences in each cable type and their use situations.

1. Flexible coaxial cable

Flexible coax uses finely stranded copper and a flexible polymer dielectric to gain its flexibility. Because it is thin, ranging from .109 inches to .405 inches, it is best used in high-speed wireless networks and connecting TVs to home video equipment.  

2. Hardline coaxial cable

Hardline cable is a thick cable with an average diameter of 1.75 inches made with a copper, steel, or aluminum center conductor and a foam dielectric. Hardline cable is best in environments where a high-strength signal is needed. This coax is hard to work with because of its thickness and requires the use of professional tools. 

3. Semi-rigid coaxial cable

Semi-rigid coax cable has a solid inner conductor but makes use of copper sheathing and polymer dielectric. It ranges from .047 inches to .250 inches in diameter. Semi-rigid coaxial works in a wide range of frequency performances and takes shape during installation. It should not be repeatedly bent after installation as this can damage the cable. 

4. Formable coaxial cable

Formable coaxial cable has the same structure as a semi-rigid coax, with a solid inner conductor and a flexible outer sheathing. Its advantage is its ability to be reshaped by hand without damaging the coax. 

5. Twin axial cable

Twin axial cable has two central conductors instead of the one that is in regular coax cable. It still has one outer conductor and dielectric. It has reduced cable loss, better protection against ground loops, and a reduction in low-frequency magnetic noise, making it a good use for video. 

6. Triaxial cable

Triaxial cable or triax has another copper braid that functions similarly to a braided shield by grounding the center conductor and protecting it from ground loops and other noise, thus increasing the signal-to-noise ratio of the cable.

Applications for coaxial cable

Coaxial cable’s versatility makes it applicable for many uses. Some of the most common uses of coax cable today are:

• Cable TV: Coax cable is commonly used for setting up wired cable TV installations as it carries television signals well over long distances.

• Satellite TV: Similar to cable TV, coaxial cables connect satellite dishes to satellite receivers and televisions inside the home.

• Home theaters: Coax transmits high-quality audio and video signals for home theater systems as it connects equipment, such as televisions, speakers, DVD players, and cable or satellite receivers.

• Cable internet: Coax internet cables are still a common delivery format for residential internet; however, fiber optic cable use grows yearly because of its increased durability and faster internet speeds. 

• Sound systems: Coaxial cable's ability to transmit audio signals at clear frequencies makes it ideal for professional sound systems and other audio setups.

• Radio applications: You can set up a ham radio with a coax cable connected to an antenna to receive radio signals, even in remote areas.

• Security systems: Good for transmitting video over long distances, coax cable is used for security cameras and CCTV systems.

Alternatives to coaxial cable

While coaxial cable is a durable and common cable type used for video, audio, internet, and other data transmission, various alternatives outperform some of coax cable’s limitations.

Fiber optic cable

Fiber optic cable is a newer technology that outperforms coax in transmission for internet and video signals by carrying signal distances several miles before another cable repeater is required. Because of its increase in speeds and distance, fiber remains relatively expensive upfront compared to coaxial cables. 

Fiber optic cable uses silicon glass strands to convert the signal into photons, which a laser or light-emitting diode transmits and then converts back to its original signal type.

Read more: What Is Fiber Optics?

Optical digital connection

Optical digital cables use fiber optic technology and mostly serve audio applications as an alternative to coax speaker cables or RCA connectors. The advantage of optical cables over coax or RCA connectors is their ability to transmit audio without interference from other electrical signals; however, optical cables are extremely fragile compared to coax and will not work if bent or twisted. 

HDMI cable

HDMI cables send audio and video signals to TVs, computer monitors, projectors, and other AV devices. Unlike coax, HDMI cables send digital signals instead of electrical ones, resulting in less interference and higher quality. For audio, HDMI cables can send high-quality digital surround sound, while coax can only send analog signals, which can be higher in quality if used purely for music. 

Ethernet cable

Ethernet cables use twisted pairs of conductors compared to the single conductor of coax cables. Ethernet cables are most commonly used to connect devices in a local area network (LAN). Two common cable types are Cat6 and Cat8. Cat6 cables can transmit data at 1 Gbps, while Cat8 cables can transmit data at 10 Gbps, making them much faster than coax cables, which transmit data at 10 Mbps. 

Who uses coaxial cables, and how to get started

Coaxial cables are primarily used in homes, businesses, and industries to connect people to television and cable service, internet service, and telephone service. You can install coax in the following places:

• Single-dwelling houses

• Large apartment complexes

• Schools

• University campuses

• Business complexes

Cable TV providers use coax to connect their customers to satellite antenna facilities, and you'll see coax lines running from telephone poles to homes and businesses in some areas to provide landline telephone service. Internet service providers use coaxial cables to provide broadband internet service to customers. You'll also find coax cables in machinery, including medical equipment, military equipment, vehicles, and speakers. 

If you're interested in a career that involves these services and working with coax, consider the following professions and their average annual salary:

*All average annual US salaries is sourced from Glassdoor as of October 2024

• Electrician: $83,601

• Cable splicer: $57,378

• Network cable technician: $64,682

• Network field technician: $65,684

• Cable technician: $56,397

• Electronics technician: $74,766

• Tower technician: $60,235

• Cable and antennae defense operations specialist: $79,653

Read more: 10 Entry-Level IT Jobs and What You Need to Get Started

Getting started with Coursera

Coaxial cables are versatile cables used in networking, audio, video, and other types of data transmission. However, new technologies like fiber optics outpace coax cables in the length they transmit data and the amount of data that passes. If you’re ready to learn more about networking and information technology, try the Google IT Support Professional Certificate on Coursera.

You can also learn more about Electric Power Systems with the University of Buffalo or Electrical Power Distribution with L&T Eductech, as well as explore the world of electronics with an Introduction to Electronics course with the Georgia Institute of Technology.