11 Types of Coaxial Cable To Know

^{Stripped coaxial cable. Image Credit: Shutterstock.com/Flegere}

Understanding the varied terrain of coaxial cables (“coax”) is essential for applying it appropriately to communications infrastructure. Fundamentally, a coaxial cable consists of a central conductor, insulating layer, metallic shield, and outer insulating layer. Widely employed for transmitting signals, coaxial cables find applications in television, internet, and telecommunications. 

The different types include Triaxial Cable, Twinaxial Cable, and Semi-Rigid Coaxial Cable. These cables vary in impedance, shielding, and flexibility, tailoring them to specific needs. These cables serve distinct purposes, offering unique advantages in specific scenarios. Understanding the broad classes of coaxial cables is vital for tailoring communication solutions to meet the demands of different environments.

This article will review 11 different types of coaxial cables, focusing on their special qualities and uses:

What Is a Coaxial Cable?

A coaxial cable facilitates the transmission of DC (direct current) over a physical medium by employing two conductors: the ‘go’ wire represented by the center conductor, and the ‘return’ wire known as the outer conductor, functioning as electrical shielding. In the realm of radio frequency transmission, coaxial cable serves as a transmission line, with the electromagnetic field contained between the inner and outer conductors. This design ensures efficient signal transfer by utilizing the outer conductor as a protective shield, enhancing the cable’s performance in various communication applications.

Why Use a Coaxial Cable?

Coaxial cables are required for their efficient signal transmission, low signal attenuation, and versatility. The concentric design minimizes signal loss and external interference, making coaxial cables ideal for telecommunications applications such as cable TV and computer networking. Their ability to transmit high-frequency signals and provide reliable connectivity reinforces their widespread use in various industries.

The Main Types of Coaxial Cables

The following are the main types of coaxial cables found in use:

1. Triaxial Cable

Unlike basic coaxial cable, triaxial cable, or “triax,” stands out for having three concentric conducting layers separated by dielectric materials. The outermost conductor provides additional shielding, which increases the triaxial cable’s resistance to electromagnetic interference. Triaxial cables have a higher bandwidth than coaxial cables.  Their greater bandwidth enables triaxial cables to be used for high-definition broadcast cameras, RF applications, and instruments like oscilloscopes and spectrum analyzers.  Triaxial cables offer versatile installation options, including direct burial for outdoor use without protective conduits and riser applications for vertical installations within buildings, meeting fire safety standards. Also, it efficiently transports data signals thanks to its two isolated shields and variety of connector styles. Triaxial cables’ robust shielding makes them ideal in environments where crosstalk, the unwanted interference between adjacent cables, is a concern, ensuring reliable signal transmission by minimizing electromagnetic interference.

2. Twinaxial Cable

Twinaxial cable, which has two central conductors twisted together instead of a single core conductor, excels in high-speed data transmission and networking applications. Coaxial cables exhibit capacitance due to the arrangement of two conductors separated by a dielectric. Twinaxial cables are constructed in such a way that they provide inherent protection against the induced field, suggesting a capacity for repelling or canceling it. Notably, twinaxial cables appear to possess lower capacitance, a desirable trait in certain applications, contributing to improved signal integrity and making them advantageous for specific purposes within the domain of data transmission and networking. Twinaxial cables support data rates up to 40 or even 100 Gbps, proving ideal for data centers, server connections, and storage devices that demand efficient data transfer. Their compatibility with various interfaces adds to their versatility, making them a preferred choice in diverse networking setups.

3. Semi-Rigid Coaxial Cable

Semi-rigid coaxial cables are distinguished from cables with braided wire shielding by having a center wire conductor that is covered in a dielectric material and shielded by a solid metal tube. They are ideal for applications operating in the microwave frequency band because of their design, which enables efficient RF signal transmission up to 65 GHz. They are more useful than RG cables for high-frequency applications because of their solid metal shielding which enables efficient signal transmission. Common diameters such as 0.141″ and 0.086″ meet a range of requirements  such as specifications for impedance, power handling, and signal integrity in a broad range of scenarios.

4. Hardline Coaxial Cable

Hardline coaxial cable finds application in the telecommunications industry, albeit not to the same extent as it once did. Its enormous diameter and strong copper, silver, aluminum, or steel construction make it useful in radio and broadcasting. Hardline coax ensures reliable signal transmission and is designed for applications requiring high power handling and outdoor durability. Some models utilize pressurized nitrogen to withstand moisture and avoid arcing, making them more appropriate for high-demand communication applications. Hardline was once utilized for long runs and broken off to RG6 or RG11 cables for communication. Though still possible, fiber optics’ ease of use and affordability have made hardline installations less common these days.

5. Rigid Coaxial Cable

Rigid coaxial cables, comprised of two copper tubes supported by PTFE supports, lack flexibility, necessitating specially designed elbows (45° and 90°) for turns/angles. These cables are mostly used indoors, but they can also be found outside on antenna masts, where they enable high-power RF component connections in TV and FM broadcasting systems. Inner bullets and flanges are necessary for interconnections. To strike a balance between conductivity, cost, and weight issues, outside conductors made of copper or aluminum accompany the copper inner conductors. However, its drawbacks include high construction costs and the need for careful moisture control to prevent excessive leakage. Commercial coaxial cables that are well selected can show very little loss—typically only a few dB over long distances. In flexible cables, physical movement must be kept to a minimum because it might cause unwanted noise and interfere with the cable’s phase shift. Rigid coaxial wires, in contrast, are more stable than flexible ones. Rigid lines are the best option for applications that prioritize strong signal integrity because they exhibit higher tolerance to interference in electrical noise-prone situations.

6. Formable Coaxial Cable

Formable coaxial cable offers a flexible and reformable alternative to semi-rigid counterparts, catering to applications requiring enhanced flexibility. Featuring a braided outer conductor typically made of tin-coated copper, this design serves to protect against corrosion. Unlike semi-rigid cables, formable ones can be stripped and shaped by hand, eliminating the need for specialized tools. While semi-rigid cables provide superior noise rejection and EMI protection due to their solid outer conductor, formable cables excel in on-site shaping and ease of installation without the requirement for specific tools or fixtures.

7. Coaxial Ribbon Cable Assemblies

Coaxial ribbon cable assemblies leverage high-speed ribbon cables through stripping or coaxial metalization. This method ensures a more controlled characteristic impedance compared to conventional bare ribbon cables, leading to elevated signal-to-crosstalk ratios. By metalizing the top and bottom surfaces of standard ribbon cables, multiple parallel miniature coaxial cables are effortlessly created. This innovative approach not only reduces manufacturing costs significantly but also streamlines production efforts in the development of high-performance, high-speed ribbon cable assemblies. Based on several metrics, these assemblies are very useful in high-speed servers and networks because they reduce skew and improve signal integrity. They are a popular option for contemporary high-speed servers, telecommunications systems, and high-performance test equipment because of the ribbonized architecture.

8. Micro-Coaxial Cable

Micro-coaxial cables, with an outer diameter of 1 mm or less, provide a compact and flexible solution for transmitting digital signals. They utilize micro coax connectors like U.FL, MHF, or AMC. Micro coax cables feature a center conductor, dielectric, and outer conductor designed for impedance matching, ensuring stability. This configuration minimizes return loss, enhancing signal integrity in communication systems. The reduced diameter of micro-coaxial cables allows their use in confined spaces, making them ideal for applications like wearable devices, medical implants, and miniature electronic components in industries where space constraints demand compact and flexible connectivity solutions. Their small diameter also makes them flexible, making them suitable for connecting the two halves of hinged devices like laptop computers. Micro-coaxial cables are used when space is at a premium. The use of space-saving grounding connectors which ground the outer conductor of the cable directly to the circuit board saves even more room in the tight confines of cellphones, GPS antennas, and other such space-constrained applications.

9. High-Frequency Coaxial Cable

High-frequency coaxial cables are designed to carry signals at higher frequencies than typical coaxial cables. Typical coaxial cables, like flexible Teflon, support frequencies up to 6 GHz, with good impedance precision and flexibility. On the other hand, high-frequency cables, such as super-flexible micro-porous Teflon, are specialized for lab use and can handle signals even up to 100 GHz. Though more expensive, ultra-flexible micro-porous Teflon cables excel in sophistication and efficiency. They have very low loss, and remarkable stability with a constant phase, and are used in flexible wirings for radio communications that are faster than 10 GHz.

10. High-Temperature Coaxial Cable

High-temperature coaxial cables, engineered for temperatures up to 200 °C, feature a PTFE (Polytetrafluoroethylene) dielectric and an outer sheath made from materials like FEP (Fluorinated Ethylene Propylene), PFA (Perfluoro Alkoxy Alkene Polymer), or PTFE. For even higher temperature requirements (250°C), cables with both dielectric and sheath made from Kapton® are available. Notable examples include RG316 (165°C), RG196 (205°C), RG188 (205°C), and Kapton 1.45 (up to 300°C). These specialized configurations ensure reliable signal transmission in environments with demanding temperature conditions.

11. Water-Cooled Coaxial Cable

The water-cooled coaxial cable design incorporates an electrically neutral, flexible center hose carrying a Cu wire braid. The cable head is soldered or otherwise secured using electro hoses that can withstand operation pressures of up to 10 bar for cooling and outer insulation. Ring-press the hose to the cable head using antimagnetic devices. There are two varieties available: hose type, which is appropriate for high mechanical loads up to 1,000V, and wire type, which is appropriate for lesser mechanical loads up to 3,000V. Melting arc furnaces employ hose types, and melting induction furnaces and associated procedures use wire types.

How Is Coaxial Cable Specified?

Coaxial cables are specified based on several key parameters. These include: impedance (commonly 50 or 75 ohms), capacitance, attenuation (signal loss over distance), and shielding effectiveness. The cable’s construction, such as the type of dielectric material and outer insulation, further define it. Standard designations such as RG6 or RG58 provide additional details about a cable’s characteristics and intended applications. Table 1 highlights some coaxial cable types and their features:

^{Table 1: Some Coaxial Cable Types and Their Features}

How To Choose a Coaxial Cable?

Choosing a coaxial cable depends on several factors including:

1. Frequency of Signal and Speed of Transmission: Different types of coaxial cables differ in their capacity to handle high-frequency signals. Make sure the cable types you consider can handle the frequency range for your application.
2. Coaxial Cable Connectors: Consider the connector types needed for your devices and systems. Different applications may require specific coaxial connector types. Ensure compatibility to establish a seamless connection and reliable signal transmission.
3. Durability and Service Environment: Consider how durable the cable needs to be, particularly if it will be installed outside or in a location with a harsh environment.
4. Device Compatibility: Ensure that the chosen coaxial cable is compatible with your devices and equipment, including TVs, radios, routers, and signal boosters. Before purchasing a coaxial cable, carefully check the types of connectors on both ends. Common connectors include F-type, BNC, and SMA. Ensure that the cable connectors match the ports on your devices. Measure the distance needed and choose an appropriate length.
5. Cost Considerations: In selecting the best coaxial cable for your needs, budget is bound to be a consideration. Prices for coaxial cables differ according to their quality and features. You may need to strike a balance between budgetary restrictions and performance capabilities, prioritizing the cable features you select based on your most important performance requirements.
6. Electromagnetic Interference (EMI): Determine what your service environment is and pick the cable shielding accordingly. You may not need to prioritize minimizing EMI if your cable will be operating in a low-EMI environment. High-density materials and several metal layers (foil and braided shields) are necessary for effective shielding. In sensitive applications like audio/video transmission or telephony, it is very important to take proactive measures to address EMI problems. Eliminating electromagnetic interference from causing signal deterioration, provides a dependable performance.

How Can Thomasnet® Help To Choose a Coaxial Cable?

Thomasnet® serves professionals in industrial buying, providing a comprehensive platform for sourcing and marketing. It extends beyond coaxial cables, offering a wealth of information, reviews, and specifications for various industrial products. This platform empowers industry professionals by creating solutions that inform, support, and facilitate effective decision-making across diverse industrial needs, including locating coaxial cable suppliers. Thomasnet® stands as a valuable resource, connecting buyers and suppliers in the industrial sector.

Does It Matter What Type of Coaxial Cable To Use?

Yes, the choice of coaxial cable type matters. The choice depends on factors such as: the length of cable run, signal frequency range, the potential for electromagnetic interference, and service conditions (indoors / outdoors). For instance, RG6 has a higher attenuation level, limiting its transmission distance and frequency range compared to RG11. RG6 can transmit signals up to 305 m, while RG11, with its lower attenuation, extends to 457 m. For a longer cable run, RG11 would be a better choice.

What Type of Coaxial Cable To Use for Antenna?

The best coaxial cable for antennas is usually RG6. Short outdoor runs and indoor installations work well with it. A longer range is possible with the quad-shielded RG6, which has additional foil shields to prevent electromagnetic interference. RG6 is the recommended material for connecting antennas because of its shielding qualities, guaranteeing dependable signal transmission.

Does the Length of a Coaxial Cable Affect the Signal?

Yes, the length of a coaxial cable does impact the signal, introducing a phenomenon known as attenuation — the gradual weakening of the signal over distance. This is influenced by the cable’s properties, such as conductor material, insulation, and shielding. For instance, in longer coaxial cables, signal loss becomes more pronounced. High-quality cables, like RG6, exhibit lower attenuation, making them suitable for transmitting signals over considerable distances with minimal degradation.

What Is the Difference Between a Coaxial Cable and a Cable?

A coaxial cable is a specific type of cable characterized by an inner conductor, insulating layer, metallic shield, and outer insulating layer. In contrast, "cable” is a broader term encompassing various types of signal transmission lines, including coaxial cables, but also fiber optic and twisted pair cables, each of which is designed for specific purposes and transmission mediums.

Copyright and Trademark Notice

1. Kapton® is a registered trademark of DuPont, Inc.