Coaxial Cable in Computer Networks

The round cable behind your TV or internet modem is a coaxial cable used to send signals like TV channels, internet data, or CCTV footage. They are built with layers to protect the signal from getting weak or mixed with outside noise. Even with the rise of fiber optics, coaxial cables are widely used because they are strong, affordable, and easy to install. In this blog, we will explore what coaxial cables are, how they work, their types, uses, and why they are important today.

Table of Contents:

• What is a Coaxial Cable?
  • Properties of Coaxial Cable
• Structure of Coaxial Cable
• How do Coaxial Cables Work?
• Coaxial Cable Types
• What is an RG Coaxial Cable?
  • Types of RG Coaxial Cable
  • Difference Between RG-59 and RG-6
• Coaxial Cable Sizes and Specifications
• Coaxial Cable Connector Types
• Fiber Optic Cable
  • Coaxial Cable vs Fiber Optic Cable
• Uses of Coaxial Cable
• Advantages of Coaxial Cable
• Disadvantages of Coaxial Cables
• Conclusion

What is a Coaxial Cable?

A Coaxial Cable is a type of electrical cable used to carry different kinds of signals, such as television signals, internet data, telephone lines, and even CCTV information. The word Coaxial Cable means “sharing the same axis”. This refers to the structure of the cable, i.e.,

• It has two conductors that carry electricity
• One conductor is placed right inside the other conductor, like a pipe inside another pipe,
• Both conductors are aligned with the same center line or axis.

This design is what makes the coaxial cable efficient at carrying signals with low interference.

The inner copper conductor is responsible for carrying the electrical signal, and around this conductor is a dielectric insulator that prevents the signal from leaking out. Then comes a metallic mesh or foil shield, which protects the signal from electromagnetic interference (EMI) and prevents signal mixing. Finally, all of these layers are wrapped in a protective plastic jacket that safeguards the cable from physical damage.

Coaxial cables can even carry Radio Frequency (RF) signals in the form of transverse electromagnetic (TEM) waves, making them ideal for both analog and digital signal transmission.

In computer networks, coaxial cables are mainly classified into two types:

• Baseband coaxial cables are used for digital signals, e.g., LANs.
• Broadband coaxial cables are used for analog signals, e.g., cable TV.

Like basic wires have noise and signal drop while transporting the signal, coaxial cables are designed to protect the signal while it travels through the cable, even over long distances. That is why coaxial cables are still used today, even with fiber optics growing in popularity.

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Properties of Coaxial Cable

Coaxial cable has the following properties:

• Layered Structure: A Coaxial cable has multiple layers that help in reducing signal loss and external interference in the transmission of the signal.
• Good Signal Transmission: Coaxial cables can transmit signals well over short to medium distances. But for very long distances, some signal loss may occur unless the signal is amplified.
• High-Frequency Handling: Coaxial cables are capable of carrying high-frequency signals, including television broadcasts, internet data, and radio signals, which makes them ideal for RF (radio frequency) and broadband communication.
• Durability and Flexibility: They are durable and can be bent or coiled easily without breaking, which makes them easy to use in homes and industrial setups.
• Shielding Efficiency: The quality and the thickness of the shielding determine how well the cable blocks interference, i.e., better shielding is equal to better signal quality transferred.

Structure of Coaxial Cable

A coaxial cable is made up of many layers, each with a specific role in transmitting data efficiently and protecting the signal. The image below shows the detailed version of the coaxial cable used for data transmission.

1. Inner conductor

This is the core component of the coaxial cable and is made up of solid copper or copper-coated steel. The main job of the inner conductor is to carry the electrical signal, such as your internet or TV signal, where the main data transmission happens.

2. Dielectric Insulator

The Dielectric Insulator is a thick layer of insulation, made of foam polyethylene, which surrounds the copper wire. It keeps the signal from leaking out or touching the other outer metal parts. It also keeps a fixed distance between the inner conductor and the shielding, which is very important for a stable signal quality.

3. Inner Shield Layer

This is a thin metal foil that is wrapped around the dielectric insulator, which reflects the signals back into the cable. It acts as the first line of defense against electromagnetic interference (EMI) and protects the external signals from entering the inner conductor.

4. Second Dielectric Layer / Padding Layer

This is the second insulation layer that can be added for extra cushioning or to separate two shield layers in the coaxial cable. It helps to maintain the structure of the cable and keep the shields protected from short-circuiting.

5. First Braided Shield / Mesh Layer

This is a metal mesh, made up of thin strands of aluminum or copper, which blocks external interference like radio waves or power lines. The tighter and denser the metal mesh is, the better the protection.

6. Second Foil Shield / Dual Shield Design

It is another metal foil shield having some cables, including a second layer for even stronger protection. This reduces signal leakage and improves noise resistance in the coaxial cable, especially for high-frequency signals.

7. Second Braided Shield / Quad Shield Design

Some high-quality cables have a second braid layer, which forms a quad shield setup for maximum signal protection. It is very useful for long cable runs or areas with high interference, e.g., near power lines.

8. Ripcord

Ripcord is a thin, string-like thread placed under the outer jacket, used to easily strip and open the outer layers of the cable during installation. It prevents damage to the inner layers when cutting the jacket.

9. Outer Jacket

This is the outermost layer of the coaxial cable made from PVC (plastic) or PE (polyethylene). It protects the cable from moisture, heat, chemicals, and physical damage.

10. Messenger Wire

It is a strong steel wire attached to the cable used in aerial installations to support the weight of the cable.

How do Coaxial Cables Work?

Coaxial cables work by transmitting electrical signals through the central copper conductor by using multiple protective layers to ensure that the signal stays strong, clean, and free from any external interference.

1. At the core of the coaxial cable, there is a copper wire, which serves as the main path for the electrical signals and the place where the actual data is present. These signals travel in the form of electromagnetic waves, moving along the conductor at high speed.
2. Surrounding this conductor, there is a dielectric insulator, which does two important jobs:
   • It keeps the copper conductor separated from the next layer.
   • It helps the signal travel efficiently by maintaining the right spacing between any two layers.
3. Outside the insulator, there is a metal shielding, made up of a braided mesh or metallic foil, which plays an important role in blocking any external electromagnetic interference (EMI). It also prevents the signal from radiating out of the cable, i.e., it protects the signal both from entering and exiting the coaxial cable.
4. Finally, the outermost layer of the cable is a plastic jacket, which is used for physical protection to keep the cable safe from moisture, bending, or any external damage. All these layers are aligned concentrically, which ensures that the signal remains stable and free from any interference, even over long distances.

Coaxial Cable Types

There are many types of coaxial cables, each of which is designed for a specific use depending on the flexibility, frequency, and performance.

1. Hard Line Coaxial Cable: It is a thick and rigid type of coaxial cable that uses a solid or metal tube for shielding instead of braided wire. It is commonly used in cable TV transmission, radio broadcasting towers, and satellite systems, where high power and low signal loss are important key features. However, it is heavy, expensive, and not flexible.

2. Triaxial Cable or Triax: It is like a coaxial cable but with an extra layer of insulation and shielding, which provides better protection against any signal interference and electrical noise. It is commonly used in professional video systems, especially in the broadcast industry.

3. Flexible Coaxial Cable: It is the cable that you find in your homes for TVs and internet connections. It uses a braided outer shield, which makes the cable soft and easy to bend around the corners. It is mainly perfect for indoor use, and it does block interference to a degree, depending on the shield.

4. Semi-Rigid Coaxial Cable: It has a solid metal outside the conductor, which makes it hard and less flexible. Because of this design, it provides excellent signal quality and low loss of signal, which is why it is often used in high-frequency applications like microwave and aerospace systems. However, it cannot be easily bent once it is manufactured.

5. Formable Coaxial Cable: It is similar to semi-rigid coaxial, but is made up of a softer metal so that it can be bent by hand. It is used in situations where performance similar to semi-rigid is needed, but with easier installation, and it is also known as conformable coax.

6. Rigid Coaxial Cable: It consists of two solid copper tubes and is mostly used in very high-power applications, like connecting broadcast transmitters to antennas. It is installed in straight sections with special connectors and cannot be bent at all.

7. Twinaxial Cable (Twinax): It has two central conductors instead of one, both surrounded by a single shield. This type of cable is mainly used for short-distance, high-speed data transfer in computer systems and networks, especially in server environments.

What is an RG Coaxial Cable?

RG stands for Radio Guide, which is a type of coaxial cable that is used to carry signals like TV, internet, video, and radio. Each RG cable has a number after it, like RG-6, RG-59, or RG-11, which helps us to tell the difference between the types of cable, i.e., how thick the cable is, how strong its shielding is, how far it can carry the signals, etc.

Types of RG Coaxial Cable

RG coaxial cables come in different types, each with a specific structure and use. Some of them are discussed below.

1. RG-58 Coaxial Cable: It is a thinner coaxial cable and is mainly used for radio communication and networking, like in old Ethernet setups.

2. RG-8 and RG-9: Cables are thicker and are used more in radio transmission or long-distance high-power connections.

3. RG-11 Coaxial Cable: It has even lower signal loss than RG-6 and is used when you need to cover longer distances without signal degradation.

4. RG-59 Coaxial Cable: RG-59 has a thinner center conductor and less shielding, making it more flexible but also more prone to signal loss and interference. It is used for short-distance, low-frequency applications such as CCTV and older analog video connections.

5. RG-6 Coaxial Cable: RG-6 has a thicker core, better insulation, and often comes with dual or quad shielding, making it ideal for higher-frequency signals and longer-distance transmission. RG-6 is the standard choice for cable TV, satellite, and internet connections, offering lower attenuation and better protection from electromagnetic interference.

Difference Between RG-59 and RG-6

Now, let us discuss the difference between RG-59 and RG-6.

Let us compare the different RG coaxial cables.

Coaxial Cable Sizes and Specifications

Coaxial cables come in different sizes and designs based on what type of signal they carry. These differences are important because they affect how well the cable performs in terms of signal quality, interference protection, and how far the signal can travel without degrading.

1. Cable Size (Thickness or Diameter)

One of the first things about a coaxial cable is its thickness because thicker cables allow the signal to travel longer distances with less signal loss, but they are also less flexible and harder to install in tight spaces. On the other hand, thinner cables are used in small devices where flexibility and compact size of the cable are more important than long-distance performance.

2. Impedance

Impedance is a measure of resistance in the cable when it carries high-frequency signals like radio waves or TV signals, which are measured in ohms (Ω). It is important to use the correct impedance for your devices because a mismatch of the cable and devices can cause signal reflections and reduce their performance.

3. Attenuation

Attenuation means the loss of signal strength as it travels through the cable. It increases with distance and frequency, meaning, the longer the cable, the more the loss there will be. Thicker cables have lower attenuation, which means they can carry signals farther without much quality loss. Thinner cables have higher attenuation and are only suitable for short distances.

4. Shielding

Shielding is the protective layer that surrounds the core wire to block external electrical interference (EMI). The better the shielding, the more reliable your signal will be, especially in environments with lots of electrical noise, like outdoor areas near power lines.

Coaxial Cable Connector Types

There are many types of Coaxial cable connectors present. Some of them are:

1. BNC Connector (Bayonet Neill-Concelman)

The BNC connector is a quick-connect type connector that uses a bayonet-style locking mechanism(a quick-connect/disconnect fastening system). It is commonly used in Television, Radio equipment, and CCTV, and is ideal for signals up to 4 GHz. It is known for its ease of use and secure connection, and is often found in lab and test equipment.

2. TNC Connector (Threaded Neill-Concelman)

TNC connectors are threaded versions of BNC connectors and offer a more secure and vibration-resistant connection. They are used in mobile phones and Wireless communication. TNC connectors can operate up to 12 GHz, making them more suitable than BNC in high-frequency or outdoor applications.

3. SMA Connector (SubMiniature version A)

SMA connectors are small, threaded RF connectors that are widely used in Wi-Fi antennas, Microwave systems, and GPS. They can handle frequencies up to 18 GHz and offer excellent performance at high frequencies.

4. SMB Connector (SubMiniature version B)

SMB connectors are smaller push-on connectors used mostly in telecommunication equipment and RF circuits where space is limited. They provide a quick and easy coupling for faster connections and are used at frequencies up to 4 GHz. They are commonly found in Telecom base stations, Circuit boards, and Low-power radio equipment.

5. QMA Connector

QMA is a quick-lock version of SMA, which is designed for faster installation and is useful in situations where frequent connection and disconnection are needed. They support signals up to 6 GHz and support wireless communication and Telecommunication systems

6. RCA Connector (Radio Corporation of America)

RCA connectors are mainly used in the transmission of audio and video signals. They are recognized by their yellow, red, and white plugs, which were the standard in older TVs and DVD players. They are not good for high-frequency signals, but they are found in analog audio systems and home theater setups.

7. F-Type Connector

F connectors are used in cable TV, satellite TV, and broadband internet systems. They work with RG-6 and RG-59 coaxial cables that support the frequency range of up to 3 GHz, and are affordable and widely available.

Fiber Optic Cable

A fiber optic cable is a high-speed data transmission cable made up of very thin glass or plastic, known as optical fibers. These fibers are even thinner than a human hair. Unlike traditional cables that carry data using electrical signals, fiber optic cables transmit data in the form of light pulses. This method allows data to move much faster, over much longer distances, and with very little loss or interference.

Coaxial Cable vs Fiber Optic Cable

Below is the difference between Coaxial Cable and Fiber Optic Cable

Uses of Coaxial Cable

Coaxial cables are widely used in various communication and broadcasting systems because they are good at carrying high-frequency electrical signals with minimal interference. Some of the most common uses are

1. Television: Coaxial cables have been the main choice for connecting cable television services. They carry both analog and digital TV signals from the service provider to the TV and allow you to receive the channels clearly.

2. HDTV: For high-quality video output, coaxial cables like RG-6 are used to transmit HD signals. They help to maintain a clean and strong signal from the antenna or satellite dish to your HDTV without any distortion or interference in the signal.

3. Internet: Coaxial cables are commonly used by cable internet providers to connect modems and routers to the internet service line. The same RG-6 cable that carries TV signals can also deliver high-speed internet, which makes it important in many homes and offices.

4. CCTV: In security camera systems, coaxial cables like RG-59 are used to connect CCTV cameras to recording devices (like DVRs). These cables can transmit video signals over moderate distances with good clarity and consistency.

5. Video Transmission: Coaxial cables are used to transmit analog video signals between devices like DVD players, projectors, and video monitors. They maintain a strong and clean signal, which is important for clear video output.

Advantages of Coaxial Cable

Coaxial Cable has the following advantages:

• Coaxial cables are simple to install and can be extended easily without any complex tools or configurations.
• These cables are cheaper and easily available, which makes them budget-friendly for home and small-scale networks.
• Coaxial cables can carry high-frequency signals, including radio frequencies and TV signals, over moderate distances, hence high data transmission.
• These cables are physically strong and can withstand rough handling and bending.

Disadvantages of Coaxial Cables

Coaxial Cable has the following disadvantages:

• Coaxial cables can be affected by electromagnetic interference (EMI), mainly in areas with heavy electrical equipment, like power transformers.

• Coaxial cables have lower bandwidth, which makes their ability to handle high-speed or high-volume data transfer slow.

• They are thicker and less flexible, which makes them harder to install in tight spaces.

• Data transmitted over coaxial cables is more susceptible to signal leakage.

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Conclusion

From the above article, we concluded that coaxial cables are used in many homes and offices to connect devices like TVs and security cameras. They have a special design that helps them to protect the signal from getting weak or mixed up. These cables are very strong, easy to use, and not too expensive. Even though fiber optic cables are faster, coaxial cables are still useful for short and medium distances. Because of their simple structure and good performance, they are a trusted choice for many everyday uses.

If you want to learn more about the Coaxial Cable and its uses, you can refer to our Computer Network Course.

FAQs on Coaxial Cable