- Published 29 Dec 2022
- Last Modified 20 Nov 2025
- 7 min
What is a Coaxial Cable and Everything You Need to Know
Discover what is a coaxial cable, how it works, its types, uses, and connectors. Learn key specs and applications with RS Australia’s guide.
Coaxial cables play a critical role in modern communication and data transmission, supporting everything from broadcast signals to internet connectivity. Their robust design and shielding make them a preferred choice in both commercial and industrial applications. In this guide, we’ll explore how coax works, the different types available, and the key considerations for choosing the right cable for your project.
What is Coaxial Cable?
A coaxial cable — often shortened to coax cable or referred to as a coax cord — is designed to transmit high-frequency signals, such as television, internet, and radio communications, with minimal loss or interference. Its layered construction allows signals to travel through the central conductor while shielding protects against electromagnetic interference (EMI), making it more reliable than standard twisted pair wiring in many applications.
The term coaxial comes from the cable’s unique design, where the inner conductor and the surrounding shield share the same geometric axis. This coaxial alignment helps maintain consistent impedance and stable signal transmission across longer distances.
Coaxial wire technology has been in use since the early 20th century and remains widely deployed in Australia for applications ranging from pay TV and CCTV to broadband internet, thanks to its durability, ease of installation, and compatibility with industry standards.
What Is RG Cable?
RG stands for Radio Guide, a designation originally developed by the U.S. military under the MIL-C-17 specifications during World War II. Each RG number (such as RG-6, RG-11, or RG-59) identifies a coaxial cable with particular electrical and physical properties, including impedance, conductor size, and shielding type.
In practice, the RG number helps engineers and installers select the correct cable for applications ranging from broadcast systems to broadband internet. The higher the RG number, the thinner the central conductor, which impacts signal handling and installation suitability.
What Does a Coaxial Cable Look Like?
A coaxial cable has a distinctive layered design that gives it a round, durable profile. Its key components include:
- Inner Conductor – Usually copper or copper-clad steel, this carries the RF signal.
- Insulation (Dielectric Layer) – Provides spacing and insulation between the conductor and shield.
- Shielding – Braided copper or foil that protects against electromagnetic interference (EMI).
- Outer Jacket – A protective plastic coating that shields the internal layers from physical damage and environmental exposure.
Coaxial Cable Sizes
Coaxial cables are often identified not only by their RG number but also by their physical dimensions. The outside diameter is a key factor that affects attenuation, flexibility, and ease of installation. Below are common sizes used in Australia:
- RG-58 – 4.95 mm (0.195″) outside diameter
- RG-59 – 6.15 mm (0.242″) outside diameter
- RG-6 – 6.90 mm (0.275″) outside diameter
- RG-62 – 6.15 mm (0.242″) outside diameter
- RG-11 – 10.30 mm (0.405″) outside diameter
- RG-12 – 14.10 mm (0.555″) outside diameter
- RG-213 – 10.30 mm (0.405″) outside diameter
The thicker the cable, the lower the attenuation (signal loss) over long distances — which is why RG-11 or RG-213 are chosen for backbone cabling, while smaller cables like RG-58 or RG-59 are used in short-run or space-constrained installations.
How Do Coaxial Cables Work?
To understand how coax cable works, it helps to look at the role of each layer in its construction:
- Signal Transmission – The inner conductor carries the high-frequency electrical signal with minimal attenuation.
- Dielectric Separation – The insulation layer maintains spacing, ensuring consistent impedance for stable signal quality.
- Electromagnetic Shielding – The braided mesh or foil prevents external EMI and cross-talk, giving coax a clear advantage over parallel wires in RF applications.
- Impedance Control – Standardised impedances (50 Ω for data and wireless, 75 Ω for video) are crucial for matching system requirements and reducing signal reflection.
- Durability – The outer jacket protects the cable from abrasion, bending, and environmental wear, ensuring reliable performance over long distances.
What Is the Transmission Speed of Coaxial Cable?
The transmission speed of coaxial cable was originally standardised at 10 Mbps in early Ethernet networks (10BASE2 and 10BASE5), offering far greater capacity than twisted pair cabling at the time. In modern applications, coax supports broadband signals up to several gigahertz, enabling internet services that reach multi-gigabit speeds under DOCSIS standards. Its shielding and impedance control make it highly reliable for transmitting high-frequency data, video, and RF signals with minimal interference.
Coaxial Cable Types
Coaxial cables are typically classified by their impedance and RG number. The two most common impedance ratings are 75 Ohm, used mainly for video and broadcast signals, and 50 Ohm, used for data, wireless, and RF applications. Within these groups, different RG numbers identify cables with specific characteristics.
RG-6
RG-6 is one of the most widely used coaxial cables, particularly for television, internet, and satellite applications. It features a larger conductor for improved signal quality, thicker dielectric insulation, and advanced shielding, allowing it to handle signals in the gigahertz range. Its relatively slim profile also makes the RG-6 easy to install in walls or ceilings, which is why it’s commonly specified in residential and commercial cabling.
RG-11
RG-11 is easily recognisable by its thicker diameter, which can make installation more challenging. However, its size gives it lower attenuation compared to RG-6 or RG-59, enabling it to carry signals over longer distances with less loss. This makes RG-11 suitable for backbone cabling, long cable runs, and high-definition video transmission where signal integrity is critical.
RG-59
RG-59 has a thinner centre conductor, making it best suited for short runs and low-frequency transmissions. It is often used in CCTV and older cable television systems, though it provides lower bandwidth compared to RG-6. Because of its flexibility and smaller size, RG-59 is convenient to install, but it is not ideal for high-frequency or long-distance applications.
RF Coaxial Cable
RF coaxial cables are designed to carry radio frequency signals and are widely used in consumer and professional applications. They are the standard type of cables for televisions, featuring a single-pin connector that plugs directly into the RF input port. Beyond TV, RF coax cables are also used in radio transmitters, antenna systems, and test equipment, thanks to their ability to transmit high-frequency signals with low interference.
What are Coaxial Cables used for?
Television & Pay TV
In Australia, coaxial cables are widely used to deliver free-to-air TV and Pay TV services such as Foxtel. RG-6 is the standard choice for domestic installations, offering strong signal quality at 75 Ohm. F-type connectors are most commonly used, ensuring stable connections for both analogue and digital television reception.
Broadband Internet
The National Broadband Network (NBN) uses coaxial cable in Hybrid Fibre Coaxial (HFC) areas, where fibre is run to the node and coax completes the final connection. RG-6 cables with 75 Ohm impedance are typically used, fitted with F-type connectors. They support multi-gigabit speeds under DOCSIS 3.1 technology.
CCTV and Security Systems
Coaxial cables remain popular in CCTV installations across Australian homes and businesses. RG-59 is often used for shorter cable runs, while RG-6 supports longer distances without signal loss. BNC connectors are the standard for surveillance cameras, offering quick locking and secure connections in demanding security environments.
Radio Communications & Antennas
Two-way radios, amateur radio, and antenna systems rely on coaxial cables to transmit RF signals. In these applications, 50 Ohm cables such as RG-58 or RG-213 are preferred. Connectors like N-type and PL-259 (UHF) are common, providing low-loss performance suitable for both professional and hobbyist use.
Other Applications
Beyond broadcast and communications, coaxial cables are used in laboratories, test equipment, and industrial control systems. Engineers select cable types depending on frequency range and run length — RG-6 for high-frequency work, RG-11 for extended distances, or RG-58 for RF testing. Connector choice varies from SMA to MCX in specialised equipment.
Coaxial Cable Splitters and Ports
What Is a Coaxial Splitter?
When coaxial cable lines are produced, they only provide one signal to power a singular device. This can be problematic if there’s more than one device which requires a signal. Coaxial splitters are used when there’s more than one device which requires a signal. They’re small devices designed to attach to coaxial cable to split the signal into several lines to connect to multiple devices.
What Is a Coaxial Port?
A coaxial port is a single female RCA connector. The port on a device is most likely to be labelled as 'coaxial', but could also be something such as 'digital out' or 'digital in'. To help distinguish it, the coaxial port is usually colour-coded orange or black.
Coaxial Cable Connector Types
Coaxial cable connectors are used to connect cables to other devices and maintain the cable’s shielding.
There are two distinct connector styles – known as male and female. Male connectors have metal pins which protrude from the centre and female connectors have a recessed hole to receive the pin.
Coaxial Cable Advantages and Disadvantages
Advantages of Coaxial Cable
- Cost-Effective: Generally inexpensive compared to other transmission media.
- Ease of Installation: Simple to wire, terminate, and expand in most environments.
- Strong EMI Resistance: Shielding minimises electromagnetic interference, maintaining signal quality.
- Durability: Outer jacket and robust design make coax suitable for long-term use.
- Stable Signal Field: The electromagnetic field remains confined between the inner and outer conductors, allowing installation alongside metal objects without significant power loss.
- High Capacity: Supports high-frequency transmission for applications such as TV, internet, and RF communications.
Disadvantages of Coaxial Cable
- Single Point of Failure: A damaged cable can disrupt an entire connected network.
- Bulkiness: Larger diameter cables (e.g. RG-11) are harder to install in tight spaces.
- Distance Limitations: Higher attenuation over long runs compared to fibre optics.
- Bandwidth Constraints: While suitable for broadband and RF, coax cannot match the capacity of fibre for ultra-high-speed data applications.
Popular Brands of Coaxial Cables
