Coaxial cable is a type of electrical cable that consists of a central conductor surrounded by an insulating layer, a metallic shield, and an outer insulating jacket.
This structure helps protect the signal from interference and allows for the transmission of high-frequency signals, making it ideal for applications like cable television, internet connections, and radio frequency transmission. Its design ensures reliable performance with minimal signal loss.
How coaxial cables work
Structure
Central Conductor: A copper or aluminum wire at the center carries the electrical signal.
Insulation: Surrounding the central conductor is an insulating layer that prevents short circuits.
Shielding: A metallic shield (often made of braided wire or foil) surrounds the insulation. This shield protects against external electromagnetic interference (EMI) and keeps the signal from radiating out.
Outer Jacket: The outer layer provides physical protection and insulation.
Signal Transmission
Electromagnetic Waves: When an electrical signal is transmitted, it generates electromagnetic waves that travel along the central conductor. The coaxial design allows these waves to propagate effectively within the cable.
Minimized Loss: The insulation and shielding prevent signal loss due to interference from external sources, making coaxial cables suitable for high-frequency applications.
Applications
Coaxial cables can carry various types of signals, including video, audio, and data, making them versatile for uses like television broadcasting, internet connections, and more.
History of Coaxial Cables
Early Developments (1880s-1920s) Inception: The principle of coaxial cable can be traced back to the late 19th century when inventors were exploring ways to enhance telegraph and telephone communication. Michael Pupin’s work on waveguides laid the foundation for coaxial designs. First Coaxial Cable: The first practical coaxial cable was developed in the early 20th century, aimed at reducing interference in signal transmission. 1930s Radio Frequency Applications: During this decade, the application of coaxial cables expanded into radio technology. Engineers recognized that the cable could effectively carry RF signals, leading to its adoption in radio broadcasting. 1940s Military Use: World War II saw a surge in demand for reliable communication technologies, prompting advances in coaxial cable design for military applications, where secure and interference-free communication was critical. 1950s Television Broadcasting Growth: As television became more popular, coaxial cables were increasingly utilized for broadcasting, connecting transmission towers to antennas and ensuring high-quality signal delivery. Development of RG Types: The introduction of specific coaxial cable types, such as RG-6 and RG-59, provided options tailored for various applications, enhancing the market's versatility. 1960s Cable Television Boom: The advent of cable TV transformed coaxial cables into a household staple. Cable companies began using coax to deliver multiple channels to homes, facilitating the growth of the industry. 1970s Broadband Internet: The introduction of broadband services led to further innovations in coaxial technology, allowing for faster internet connections. The use of DOCSIS (Data Over Cable Service Interface Specification) standards enabled cable providers to deliver high-speed internet via existing coaxial infrastructure. 1980s-1990s Digital Transition: The digital revolution necessitated upgrades in coaxial cable technology to support digital signals, leading to improved performance in data transmission and quality. 2000s and Beyond Modern Applications: Coaxial cables remain widely used in various fields, including telecommunications, video surveillance (CCTV), and internet services. Advancements in materials and shielding techniques have further enhanced their reliability and bandwidth capabilities. Integration with Fiber Optics: In many modern installations, coaxial cables are used in conjunction with fiber optics to create hybrid systems, leveraging the strengths of both technologies. Legacy Coaxial cables have played a crucial role in the evolution of communication technologies, demonstrating remarkable durability and adaptability. They continue to serve as a fundamental component of many telecommunications systems today, highlighting their enduring significance in the industry.
Types of coaxial cables
Coaxial cables can be divided into a number of subclasses, all of which are specifically tailored for certain purposes and performance levels. To name a few, the most common ones are:
RG-6 Use: There is a popular use of this for dispatch of cable TV and internet DPS systems. Features: Provides output, shielding and also bandwidth for high frequency signals; extended lengths.
RG-59 Use: This type of cables is the older one and is used to transmit lowfrequency signals of camera CCTV and for a standard video. Features: It is able to carry some of weight on distance compare to RG-6 and this means lower signal loss in long distance.
RG-11 Use: These are normally recommended for long-haul links, which are applicable to cable TV and satellite systems. Features: It is much thicker than RG-6 with less attenuation, which makes it suitable for high quality transmission even over longer distances.
RG-8 Use: It is a transmission line that is mainly used in radio communication and also in amateur radio. Features: Wide width for smooth operations, making it ideal for higher frequencies.
RG-213 Use: In radio frequency applications, especially in military and commercial areas, these cables are also implemented. Features: Its performance is similar to that of RG-8 but provides better shielding and reduced loss.
LMR Series Use: It has a wider application in wireless communications and services. Features: Designers have made this equipment flexible and lightweight, thus, there is low loss and high frequency.
Mini Coaxial Cables Use: Therefore, they usually come in handy in spaces where smaller and bendable cables are often needed, like in cameras or gadgets. Features: Space saving design that saves on height, but still produce performance.
Foam Dielectric Coaxial Cable Use: They are used in frequency range of microwave and beyond, i.e., telecommunications and broadcasting. Features: Due to the foam dielectric materials, which are used by the cable, such cables are lightweight and have lower loss which gives a good insulation.
Hardline Coaxial Cable Use: Messengering between telecom and broadcasting systems by outdoor applications. Features: The components are well structured and stiff, having a high degree of improvement effective shielding with extraordinary performance over long distance.
Uses of coaxial cables
Coaxial cables are used in many different ways because of their robustness and capacity of transmitting high wireless signals with almost no noise. A strong determination of uses is as follows:
Cable Television All cable TV viewers, no matter any kind of service, will have connectivity problems if the coaxial cables fail to bring the cable TV signals properly to their homes. This enables multiple channels and high-definition content as well.
Internet Connectivity Most services that give broadband connections normally use coaxial cables to connect the homes and businesses to the internet. This is more so if you are on cable modem systems.
Radio Frequency (RF) Transmission) Coaxial cables are used for the AM and FM radio stations' broadcast by transmitting RF signals through them.
Closed-Circuit Television (CCTV) In building CCTV systems, coaxial cables serve the purpose of transmitting video signals from the cameras to recording devices or monitors.
Data Networking Early Ethernet networks (such as the 10BASE2 and 10BASE5) utilized coaxial cables as the aspect of transmission (these have by now been replaced mainly by fiber optic and twisted-pair in these days).
Telecommunications Telecommunications make use of coaxial cables to transport voice messages and data signals among long distances, usually, the cables are operated with other technologies.
Military Applications Coaxial cables in military communications systems play a very vital role in the transmission of secure and reliable data.
Home Audio and Video Systems These types of cables are normally fitted to connect several audio and video devices. Therefore, such cables can transmit high quality audio signals such as S/PDIF and also the video signals like composite video.
Computer Graphics and Video Applications Coaxial cables find application in some apps such as the graphic design and video applications which connecting graphics applications and monitors and graphics outputs connecting via the cables.
Amateur Radio One of the common things amateur hobbyists do is to connect external antennas to transmitters which is built into the coaxial cable, enjoying benefits, from efficient to lower signal losses at the RF frequencies.
Common coaxial structures
Solid Conductors
Solid copper conductors are popular on many CCTV installations. Solid conductors provide less chance for distortion and line loss than copper covered steel. However, copper is a soft material and will break if repeatedly flexed. It is best used on permanent installation.
Depending upon the application, many different types of conductor constructions may be found in coaxial cables.
Stranded Conductors
Many small strands of copper can be used to make up any gauge size. Stranded conductors provide increased flexibility over solid conductors. This design has become popular for use on pan and tilt cameras, robotics and other applications that require repeated flexing.
Copper-Covered Steel Conductors
In some applications strength is a key requirement. Steel conductors covered with copper may be needed to prevent breakage in an active environment. Copper covered steel conductors provide added strength and RF support and are often used in CATV and MATV applications.
The Dieletric
The inner conductor of a coaxial cable is separated by an insulating material from the surrounding shield(s). This "dielectric" material is often chosen in order to maintain consistent electrical properties and minimize signal loss. The result is a clear, trouble-free transmission.
Note: foamed dielectric materials provide a lightweight composition suitable for many coaxial constructions. Foaming the dielectric also contributes to increased clarity in high-speed transmissions.
Popular Dielectric Materials include:
PE-Solid Polyethylene: good for low-temperature applications.
FPE-Foamed Polyethylene: provides lower attenuation and capacitance than solid PE.
Air-Spaced: supports a lower dielectric constant than Polyethylene while allowing for a small diameter cable size.
FEP-Fluorinated Ethylene Propylene: excellent for high temperature and plenum applications. Low dielectric constant for clear signal transmission.
In coaxial applications, shielding is an important part of the overall composition of the cable. Shielding not only protects the loss of signal in the high-frequency application but also helps to prevent EMI (electromagnetic interference) and RFI (radio frequency interference) in the circuit. There are three popular types of shielding available from Coleman/CCI: overall foil, braid and foil/braid.
Foil Shield
Foil shields are commonly used as an effective, low-cost application to prevent EMI/RFI interference. The construction consists of a layer of aluminum with a polyester backing that is overlapped to provide 100% coverage.
Braid Shield
Braid shields are constructed of thin strands of aluminum, copper coated aluminum tinned copper or bare copper that are interwoven. Many different coverages are available with 40-67% aluminum and 95% copper being the most popular. High percentage braided shields offer an excellent protection from EMI and RFI and are popular in CCTV applications.
Foil/Braid Shield
Foil/braid shielding is extremely popular with CATV and MATV applications. The 100% aluminum foil is accompanied by a braided shield to provide improved protection from EMI and RFI.
Tri-Shield
Construction consists of a foil-braid-foil-shield.
Quad-Shield
Construction consists of a foil-braid-foil-braid shield. Very popular for CATV and MATV applications in high EMI/RFI locations such as urban areas.
The Jacket
The outer sheath found on most coaxial cables is called the jacket. The main function of the jacket is for protection from the environment and mechanical damage as well as an additional form of insulation. The compounds used to make the jacket may have different temperature ratings. The temperature rating of a cable, along with the location rating (i.e. plenum, wet, sunlight resistant etc.) will determine the minimum or maximum operating temperature of the cable. In today’s multi-application world, many jacketing choices exist:
PVC-Polyvinyl Chloride: Very flexible thermoplastic material commonly used for general purpose coaxial products. Temperature rating: -40 to 80°C.
PE-Polyethylene: A thermoplastic material which exhibits excellent electrical properties. Often used in direct burial applications. Temperature rating: -55 to 85°C.
FEP-Fluorinated Ethylene Propylene: A thermoplastic material with good insulating properties. Excellent in high temperature, plenum, and chemical environments. Temperature rating: -50 to 200°C.
Coaxial cable uses two conductors that share a common axis. In triaxial cable, there are three conductors that share an axis. Twinaxial is different because it uses two twisted conductors surrounded by a common shield. The conductors in twinaxial cable don’t technically share an axis but are twisted together, giving the cable the “feel” of a shared axis.
We carry a large selection of coaxial cable products including triaxial, twinaxial, low loss coax cable, low noise, high power, and high temperature options. We also distribute RG coax cable products manufactured by Belden Cable and Alpha Wire Company.
Coaxial Cabling is designed for the transmission of high frequency signals with a minimum of loss. Coaxial wire and cable is offered with various configurations, and the most common ones are listed on the previous page. When purchasing coaxial cable, you should consider impendence, environmental temperature, working voltage, signal loss at specific frequencies, power rating and cost. If a type of coax cabling is not listed please contact our sales department.
RG6 cable is heavier gauge and has thicker insulation and better shielding. It is best for high bandwidth or high frequency applications such as Internet, Cable TV, and Satellite TV signals. If you aren’t sure which cable to get then RG6 cable is your best bet
RG59 cable is thinner and has less shielding. It is only recommended in low bandwidth and lower frequency applications such as CCTV installations
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