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Coaxial Cable, often called coax, is a lifeline for the telecommunications industry. This includes high-grade lines and sub-fiber cables that cable television operators, telephone companies, and Internet service providers use to transmit data, video, and voice communications with their customers. This guide explains coaxial Cable in detail, including its structure, types, applications, advantages over other cables (including ones called better), and disadvantages.
What is Coaxial Cable?
Coaxial Cable, also known as coax cable, is a type of Cable used to carry electrical signals at high frequencies along a conductor surrounded by an outer conductor. It differs from traditional wires because it has multiple layers to provide insulation around its signal-carrying core and shield the signals from outer interference such as walls or floors. The core conductor is surrounded by a dielectric insulator enclosed in a metallic shield. This shield considerably blocks electromagnetic interference (EMI) and avoids signal loss. As a result, the signal can still be reliably transmitted over long distances of wire.
Structural Features of Coaxial Cable
Commonly known as coax cable, coaxial Cable plays a vital role in telecommunications: it enables data, video, and voice communications to travel from providers like cable television companies, telephone carriers, and internet service providers to their customers.
This guide will comprehensively understand coaxial Cable, from its structure and categories to applications, advantages, and disadvantages.
What is Coaxial Cable?
Coaxial Cable is a transmission line that carries high-frequency electrical signals with low loss. It differs from traditional cables, comprising multiple layers of insulating, shielding, and protecting the signal-carrying core. Inside the Cable, a copper wire passes through a dielectric layer enclosed by an aluminum or plastic sheath; this structure effectively inhibits electromagnetic interference (EMI) while minimizing signal attenuation over long distances, thus ensuring reliable long-distance transmission.
Structural Features
Coax consists of four main parts:
- Core Conductor: The inner conductor is typically solid (see skin effect for high-frequency signals), while hollow copper tubes or copper-clad aluminum bars are used. Copper-clad aluminum wires are suggested for distribution networks or backbone lines to reduce weight and cost while providing optimal transmission.
- Dielectric Insulator: The insulating material may be polyethylene, polypropylene, polyvinyl chloride (PVC), and fluoroplastics. Polyethylene is widely used because of its low loss (at frequency) and outstanding processing performance.
- Braided Shield (Outer Conductor): The braided shield acts as both the transmission circuit of the conductor and shielding. There are three kinds of structures:
- Tubular Metal: Made by longitudinal soldering copper or aluminum foil or by extruding and drawing seamless copper tubes. This structure ranks first in shielding performance but has poor flexibility.
- Aluminum-Plastic Composite Foil Longitudinal Overlap: This has a good shielding effect and is low-cost to produce.Tubular Metal: This offers good shielding performance, and then an Overlap Security gap Aluminum-PVC Composite Foil on the propionate Laminated seems inevitable, with such few seams interrupting signal paths.
- The combination of Braided Shield and Aluminum-Plastic Composite Foil Longitudinal Overlap provides good flexibility and reliable joints, making it widely used.
- Protective Plastic Layer: Black polyethylene with excellent weather resistance is preferred for outdoor cables. Light-colored polyethylene is used for aesthetic reasons for indoor cables.
Functionality
Coaxial Cable conducts alternating current (AC), meaning the current direction reverses multiple times per second. Ordinary wires act as antennas and radiate energy when used to transmit high-frequency currents, causing signal loss and leakage. The unique coaxial cable design avoids this problem by using the inner conductor to carry the signal and the outer conductor to shield it from external electromagnetic fields. The dielectric material between the conductors ensures consistent impedance along the Cable’s length, optimizing signal transmission.
Specific Classifications
Coaxial Cable is divided into several categories based on its characteristics and applications:
Standard Coaxial Cable
It is widely used in communication, broadcasting, and television fields. It offers high bandwidth, stable signal transmission, and strong anti-interference capabilities, making it suitable for cable TV and broadcast television.
RG Series
Standardized for video signal transmission and computer network connections. The RG series is known for stable impedance and long transmission distances, and it is suitable for long-distance video surveillance and network transmission. Common types include RG59 (short-distance), RG6 (medium-to-long-distance), and RG11 (long-distance).
Low-Loss Coaxial Cable
Used for high-frequency signal transmission, featuring low-loss insulation and high-quality conductor materials. It is widely used in wireless, satellite, and other fields, improving signal transmission quality and distance.
High-Temperature Coaxial Cable
Designed to operate in high-temperature environments using high-temperature-resistant materials. They are used in aerospace, military equipment, and other fields requiring high-temperature signal transmission.
Lightning Protection Coaxial Cable
It uses unique materials and structural designs to prevent lightning interference and damage to signal transmission. It is used in radars, communication base stations, and other places requiring lightning protection.
Submarine Coaxial Cable
They are used for underwater communication with unique waterproof materials and sealing structural designs. They are also used in submarine optical cables, marine observation, and other underwater communication needs.
The Types of Connectors
Coaxial cable connectors come in various types, each designed for specific applications and frequency ranges. Some common types include:
- Bayonet Neill-Concelman (BNC): Used for television, video, and radio signals under 4GHz.
- Threaded Neill-Concelman (TNC): Used for telephony applications with frequencies up to 12 GHz.
- SubMiniature version A (SMA): Used in mobile phones, Wi-Fi antennas, microwave system,s and radios with frequencies up to 18GHz.
- SubMiniature version B (SMB): Used in telecommunications hardware.
- Quick-locking SMA (QMA): Rapid-opening SMA connectors for industrial and communications electronics use.
- Radio Corporation of America (RCA): Used with audio and radio signals often found on older TV sets.
- F Connector: Commonly used for digital and Cable TV applications using RG-6 or RG-59 cables.
Applications
Coaxial Cable is widely used across various industries and applications, including:
- Television: Transmits the signal for a television set, with cable TV using 75 ohm RG-6 coaxial Cable.
- Internet: Carries internet signals, often via RG-6 cable.
- CCTV: Used in Closed Circuit Television (CCTV) systems, RG-59 and RG-6 cables suit the job.
- Video: RG-6 is a medium for video transmission, used in digital signals, and RG-59 is suitable for lossless analog video transmissions.
- HDTV: High Definition Television (HDTV). It uses an RG-11 coaxial cable for higher signal transmission.
Advantages
Coaxial Cable offers several advantages over other types of transmission media:
- Low Signal Loss: Enables efficient signal transmission over long distances.
- High Bandwidth: Supports a wide frequency range, suitable for transmitting high-bandwidth signals like video, voice data, and others, as well as low-frequency data-intensive applications.
- Strong Anti-Interference Capability: With excellent EMI/RFI protection, the signal remains sanitary.
- Long Transmission Distance: It transmits signals over long distances without significant degradation, which is ideal for telecommunications and broadcasting applications.
- Versatility: Can be used in various applications, including cable television, internet connections, closed-circuit television surveillance systems, and telecommunications networks.
Disadvantages
Despite its many advantages, coaxial Cable also has some limitations:
- Cost: It can be more expensive than similar types of transmission media, such as twisted-pair Cable or fiber optic cable.
- Bulkiness: This type of Cable is bulkier and less flexible than most other types, so it is unsuitable for tight spaces or applications that require a lot of mobility in their installation.
- Complexity of Installation: Installing coaxial Cable may require special tools and techniques, especially in outdoor or long-distance installations.
- Limited Bandwidth: While it has a high bandwidth relative to twisted-pair copper cable, it is still far from the capacity of optical fibers, which can theoretically carry all data ever produced.
- Susceptibility to Damage: This can be susceptible to physical damage, such as cuts or kinks, that can affect transmission.
Interference Issues
Coaxial cables can experience various types of interference, including signal leakage, external noise, and electromagnetic interference (EMI). Signal leakage occurs when electromagnetic fields penetrate the Cable’s outer shielding, resulting in signal loss. External signals may also leak through the insulation, causing additional interference.
FAQs
- How to dress coaxial cables on a telephone pole？
Use cable ties and spacers to secure the Cable, ensuring minimal stress on the connector. - What size of coaxial Cable is for exterior use?
RG6 cables are commonly recommended for outdoor applications due to their weather-resistant properties. - How many ohms are in the RG-58 coaxial cable?
RG-58 cables typically have an impedance of 50 ohms. - How do you test coaxial Cable?
Use a multimeter or cable tester to check continuity and signal strength. - How to join coaxial cables?
Use coaxial couplers or compression connectors for a seamless connection.
Conclusion
Coaxial Cable is a versatile and reliable transmission medium used in telecommunications, broadcasting, and networking. Its unique design provides low signal loss, high bandwidth, and strong anti-interference capabilities, making it ideal for transmitting high-frequency signals over long distances. While its limitations include cost and bulkiness, its numerous advantages make it an essential component of modern communication systems.
As technology evolves, coaxial Cable remains critical for ensuring reliable and efficient signal transmission in various industries and environments.
Need help with your customized coaxial cables or consulting solutions?
Romtronic is China’s leading and most innovative professional cable assembly manufacturer and wire harness wiring factory. We have 28 years of OEM and ODM experience in medical, industrial, and automotive cables and can provide technical support and customer service.
Call the experts at Romtronic today at +86 199-2816-5824 or email us at info@romtronic.com.
If you need to know more about RF connectors, please click to view RF Connector Basics.
Apple Liu, Romtronic’s Marketing Manager, specializes in driving Asian market growth. With a degree in International English and eight years of sales experience in the electronic cable and harness industry, she brings deep industry expertise and a global perspective. She is passionate about Romtronic’s leadership in digital engineering and is dedicated to advancing the brand’s presence and innovation.
