Explore the unique design and functionality of coaxial cables versus standard shielded cables. Learn how their specialized construction enables superior signal transmission, and find the perfect coax cable for your needs.
Table of Contents
What Is a Coaxial Cable?
A coaxial cable is a type of electrical cable designed to transmit radio frequency (RF) signals with minimal interference. Coaxial cable is also known as coax. It features a unique structure that consists of a central conductor surrounded by an insulating layer, a metallic shield, and an outer insulating layer. This design allows coaxial cables to carry data, video, and audio signals over long distances with high efficiency and low signal loss.It transmits analog and digital electrical signals over radio frequencies from 20 kHz to 300 GHz. People often refer to coaxial cables by the type of connection, such as “RCA” or “XLR.” So you may have used more than one type of coaxial cable without realizing it.
Structure of Coaxial Cable
Coaxial cables are characterized by their layered structure:
- Inner Conductor: The solid or stranded wire that carries the electrical signal.Typically made of copper or copper-clad steel, this is the core that transmits the signal.
- Dielectric Insulator: Surrounding the inner conductor, this non-conductive material prevents signal leakage and provides insulation.
- Outer Shield: A woven copper braid or aluminum foil layer that protects the signal from external electromagnetic interference (EMI).
- Outer Jacket: A plastic or rubber layer that encases the cable, it is not used to carry information but providing physical protection and environmental resistance.
How Do Coaxial Cables Work?
Coaxial cables consist of concentric layers of electrical conductors and insulating material that ensure signals are protected and free from interference. The inner conductor, typically made of solid or braided copper, transmits the electrical signals. Surrounding this conductor is a dielectric layer, made of insulating material with well-defined electrical properties, which confines the signal within the cable and prevents leakage. This layer is then encased in a metallic shield, usually made of braided copper or metal foil, which blocks external electromagnetic interference.
The entire structure is wrapped in an insulating outer jacket to protect it from environmental factors. The outer shield layer is connected at both ends via connectors to filter out unwanted transmission and ensure signal clarity. This design enables coaxial cables to maintain signal integrity over long distances, making them ideal for applications like television broadcasting, internet connectivity, and telecommunications.
What Are The Different Types of Coaxial Cables?
Coaxial cables differ in design depending on their end use.Shorter cables are commonly used in household systems such as AV setups or personal Ethernet connections. Longer cables are ideal for connecting extensive networks, such as radio, television, or long-distance telecommunication lines. Additionally, micro and mini coaxial cables play crucial roles in consumer electronics, military equipment, aerospace systems, and medical devices due to their compact and versatile design.
Below are some of the most common coaxial cable types and the applications they support.
Hardline Coaxial Cables
Hardline coaxial cables feature a rigid outer conductor made of aluminum or copper, has a larger diameter(≥ ½-inch diameter) when compared to other coaxial cables.These coaxial cables are commonly used in telecommunications and high-power signal transmission due to their durability and low signal loss.
Flexible Coaxial Cable
Flexible coaxial cables are highly adaptable and designed to bend and move without compromising signal integrity. These cables feature an inner conductor surrounded by a flexible polymer dielectric layer, allowing for easy routing in tight spaces. They are commonly used in applications where frequent cable movement or flexibility is required, such as in robotics, consumer electronics, and portable communication devices.
Formable Coaxial Cable
Formable coaxial cables serve as an alternative to semi-rigid cables, offering similar performance with added flexibility. Instead of a rigid copper outer sheath, these cables utilize a flexible metal sheath that can be shaped and bent during installation. This makes them ideal for applications requiring precise routing, such as in aerospace, medical equipment, and custom communication systems.
Radiating Coaxial Cable
Radiating cables, also known as leaky cables, are designed with slots in the outer conductor to allow signal leakage. These cables are ideal for applications in tunnels, mines, and other environments where regular wireless signals struggle to propagate.
Twinaxial Coaxial Cable
Twinaxial cables consist of two inner conductors surrounded by a single outer shield. They are often used in short-range data transmission applications, such as in high-speed computer networks.
Triaxial Coaxial Cable
Triaxial cables have an additional layer of insulation and shielding, providing better protection against interference. These cables are commonly used in professional video equipment and high-security data transmission.
Semi-Rigid Coaxial Cable
Semi-rigid coaxial cables feature a solid metal outer conductor, offering excellent shielding and performance. They are typically used in applications requiring precise signal transmission, such as aerospace and military systems.
Rigid Line Coaxial Cable
Rigid line coaxial cables have a solid metal outer conductor and are designed for permanent installations in high-power applications, such as broadcast antennas.
RG-6 Coaxial Cable
RG-6 cables are among the most common types of coaxial cables, primarily used for relaying cable television signals. The central conductor is made of either copper-clad steel (CCS) or bare solid copper (BC), providing a balance between strength and conductivity. Originating from the WWII-era military specification “Radio Guide,” RG-6 cables have evolved into four specific variants for different applications:
- Standard: Designed for typical indoor and outdoor home wiring.
- Flooded: Features additional waterproof gel, making it suitable for underground conduits.
- Messenger: Incorporates a steel wire to handle the tension of aerial drops between utility poles.
- Plenum: Encased in a PTFE (polytetrafluoroethylene) jacket to meet fire safety codes for use in air handling spaces and ventilation ducts.
Coaxial Cable Connector Types
There are so many types of coaxial connectors on the market, how should they be used together? Because there are so many, it may take some time to explain them one by one. Here is a brief introduction to the ten most commonly used styles: F-type, BNC, TNC, SMB, MCX, SMA, RCA, UHF and 7/16 DIN. The above styles of connectors are all “adapted” to each other in the form of male/female, plug/jack. It may be a male or female plug, or a male or female jack. Male and female are often also called polarity.
F-type Connector
The standard “cable” connector most commonly used for cable TV or Internet connections.They are commonly found on RG-6/U cable.
Bayonet Neil-Concelman (BNC) Connectors
The abbreviation of Bayonet Neil-Concelman, used to describe its connection style, because the bayonet style is suitable for quick twist-on connections. Miniature to subminiature in size, these RF coaxial connectors allow you to quickly connect with and disconnect from television, radio, RF equipment, and testing instruments.
Threaded Neil-Concelman (TNC) Connectors
Some may think this connector works with BNC because of the similar names, but TNC is short for Threaded Neil-Concelman, which is simply a threaded and weather-resistant version of BNC. Operating at 12GHz, it is suitable for creating RF/antenna and cell phone connections while minimizing stability and leakage issues.
Subminiature version B (SMB) Connectors
Compact connectors with an easy snap-on design, ideal for semi-rigid cables in applications requiring infrequent connections. They provide excellent electrical performance from DC to 4 GHz.
7/16 DIN
7/16 Deutsches Institut für Normung (DIN) connectors. This style is defined as 7 mm and 16 mm DIN. DIN refers to the organization that originally standardized the connector styles – Deutsches Institute Fur Normung (German Institute for Standardization). This style is most popular in cellular antenna applications.
Micro Coaxial (MCX) Connectors
This is another style that has multiple variations. MCX stands for Micro Coaxial Connectors, which is closely related to connectors such as MMCX (Micro-Miniature Coaxial Connector), MMBX, SMB (Sub Miniature Version B), SSMB (Smaller SMB), SMC, SSMC, SSMCX, etc. All of the above connectors have a snap-on connection and are not generally cross-connected.
Radio Corporation of America (RCA) Connectors
The RCA connector is named after the company that designed it, Radio Corporation of America. This is a very common connector used for basic and fast video and audio connections. You will see these red, white, and yellow wires on the back of your television. Also called a cinch connector, the RCA connector is easily recognizable by the ring surrounding the male connector end.
UHF Connector
The UHF connector, commonly referred to as the Amphenol coaxial connector, stands as a standardized 50 Ohm RF connector designed specifically for low-frequency radio applications. This versatile connector has found widespread adoption in various radio communication systems, including amateur radio operations, citizens’ band (CB) radio equipment, and marine VHF radio installations. While it demonstrates reliable performance in these applications, it’s important to note that its effective operating range typically extends up to 300 MHz, making it particularly well-suited for lower frequency RF transmission requirements in these domains.
SMA Connector
SMA (Subminiature Version A) connectors represent a compact interface designed for coaxial cable connections featuring a threaded coupling system. These connectors maintain a consistent 50 Ohm impedance rating and demonstrate remarkable versatility, operating effectively across a frequency range from DC (0 Hz) up to 18 GHz. Their reliable performance and small form factor make them particularly well-suited for various applications, including microwave equipment installations, portable radio devices, and cellular antenna systems. The SMA connector’s combination of size efficiency and broad frequency capabilities has established it as a standard choice in RF and microwave engineering.
Key Factors to Consider When Choosing a Coaxial Cable
Choosing the right coaxial cable involves evaluating the application, environmental conditions, impedance requirements, and the cable’s physical properties. A well-matched cable ensures efficient signal transmission, durability, and system reliability. Always consider the specific needs of your project to make an informed decision.
Coaxial Cable Length and Thickness
The length and thickness of the coaxial cable significantly affect its performance. Longer cables can lead to signal loss, so it is essential to choose a cable length that minimizes attenuation while meeting your needs. Thicker cables typically offer lower resistance and are more suitable for long-range transmissions.
Coaxial Cable Impedance (Ohms)
Impedance, measured in ohms, is the resistance a cable presents to alternating current. Matching impedance throughout the cable system (e.g., 50 ohms for RF applications or 75 ohms for video) is crucial to avoid signal degradation, echoes, and ghosting in TV signals.
Coaxial Cable Passive Intermodulation (PIM)
PIM is a form of signal interference that can degrade performance in communication systems. Low-PIM cables are critical in applications where high signal quality is essential, such as cellular networks.
Coaxial Cable Jacket Rating
The outer jacket of the coaxial cable protects it from environmental factors. Depending on your application, you may require cables with specific jacket ratings, such as UV-resistant, waterproof, or flame-retardant properties. Consider the environment where the cable will be installed (e.g., outdoor, underground, or high-heat areas).
Coaxial Cable Connectors
The type of coaxial cable connectors used is vital for compatibility and signal integrity. Ensure the connectors match the impedance of the cable and the devices you are connecting. High-quality connectors can reduce signal loss and improve overall system performance.
Coaxial Cable Application
Different coaxial cables are designed for specific uses, such as military operations, broadcasting, or general consumer electronics. Determine your application’s range and frequency requirements before selecting a cable. For example:
Short-range, low-frequency needs may only require basic RG6 cables.
High-frequency or long-range applications may demand specialized cables with additional shielding.
Coaxial Cable Environment
Environmental factors such as moisture, sunlight, and corrosive elements can affect the cable’s lifespan and performance:
Underground cables should be housed in waterproof conduits.
Outdoor cables might require UV-resistant or armored jackets.
For harsh environments, consider cables with tin or silver coatings for added protection.
Working Voltage and Power Rating
Coaxial cables have a maximum voltage rating, determined by the dielectric material and conductor. Always choose a cable with a working voltage that exceeds your system’s requirements to ensure safety and reliability.
Signal Loss at Specific Frequencies
High frequencies (VHF and UHF) can experience significant signal loss. Manufacturers often use foil or braided shielding to minimize interference and maintain signal quality. Review the cable’s specifications to ensure it meets your frequency requirements with minimal loss.
Common Applications — What Are Coaxial Cables Used For?
Coaxial cables serve as crucial components in numerous telecommunications and signal transmission applications. Their unique design, featuring a central conductor surrounded by insulation and shielding, makes them ideal for carrying various types of signals while minimizing interference and signal loss.
Television and Video Systems
- Cable TV distribution from providers to homes and businesses using 75 Ohm RG-6 cables
- HDTV installations utilizing RG-11 cables for enhanced signal capacity
- CCTV systems employing both RG-59 and RG-6 cables
- Connection of TVs to antennas and satellite receivers
- Video transmission, with RG-6 preferred for digital signals and RG-59 for lossless analog transmission
Internet and Data Transmission
- Broadband internet service delivery from cable providers to homes
- Connection between cable modems and main cable lines
- High-speed data transmission with minimal attenuation loss
- Last-mile connectivity to individual residences and offices
Cellular Communications
Cell phone signal boosters, comprising:
- Connections between outdoor antennas and amplifiers
- Links between amplifiers and indoor antennas
- Bypass of signal-blocking building materials
- Enhancement of indoor cellular reception
Radio Communications
- Ham radio antenna connections for stronger signal transmission
- Basic RF (Radio Frequency) systems
- Radio equipment installations
- Signal transmission in remote locations without requiring internet infrastructure
The choice of specific coaxial cable types depends on the application:
- RG-6: Commonly used for digital signals in television, internet, and video applications
- RG-59: Preferred for analog video transmission and CCTV systems
- RG-11: Specialized for HDTV applications requiring greater signal capacity
Advantages and Disadvantage of Coaxial Cable
Coaxial Cable Advantages
- High bandwidth and signal-carrying capacity.
- Effective shielding against electromagnetic interference.
- Durable and cost-effective.
Coaxial Cable Disadvantages
- Bulky and less flexible compared to other cables.
- Signal loss over very long distances without amplification.
- Limited scalability for high-speed data applications.
Some FAQs
What is a coaxial cable's transmission speed?
Coaxial cables can transmit data at speeds up to 1 Gbps or higher, depending on the cable type and application.
What are the main coaxial cable advantages?
Coaxial cables offer high bandwidth, excellent shielding, and reliable signal transmission over long distances.
What is the Difference Between RG-6 and RG-59 Coaxial Cable?
- RG-6: Thicker dielectric insulator and better shielding, suitable for higher frequencies and longer distances.
- RG-59: Thinner and less shielded, better for short-distance, low-frequency applications like CCTV systems.
Can coaxial cables be installed outdoors?
Yes, but outdoor installations require weather-resistant cables with UV protection and waterproof connectors.
How do I identify the type of coaxial cable?
Check the labeling on the cable jacket, which typically includes the cable type (e.g., RG-6, RG-59) and specifications.
Conclusion
Coaxial cables are versatile and widely used in various applications, from broadcasting and internet connectivity to high-speed data transmission. Understanding the different types, structures, and uses of coaxial cables helps in choosing the right one for your needs. With their reliable performance and durability, coaxial cables remain a cornerstone of modern communication systems.
