Everything You Need To Know About Coaxial Cable

Coaxial cables are vital for transmitting radio frequency signals in New Zealand, used in applications ranging from residential TV and internet to industrial telecommunications infrastructure. This article explores the various parts and types of coax cables, how they work, and what they are used for.

A coaxial cable has a distinct thick, round shape due to its interior insulation layer. This makes it easily distinguishable from other types of cabling, such as the thinner, more flexible twisted-pair or Ethernet cables commonly used in New Zealand homes and offices. The most commons sizes and types of coaxial cable are RG-6, RG-11 and RG-59 – some of the size differences are demonstrated in the image below.

Coaxial cables are available in a variety of colours including black, brown and white.

The shielded design of coax cable makes them a popular choice for signal transmission. This design protects the central conductor from damage and interference, enabling efficient data transfer.

A coaxial cable is typically composed of four distinct layers:

• Centre Conductor: This is the pathway for data and video signals. It is usually copper wire.
• Dielectric Insulator: A plastic layer surrounding the conductor. It maintains spacing and provides insulation.
• Shielding: A braided mesh, often made of copper. Protects the cable from electromagnetic interference (EMI) and minimises signal loss (attenuation).
• Outer Jacket: A plastic coating. Protects the internal layers from physical and environmental damage.

The different layers of a coaxial cable are shown in the image below:

Coaxial cables offer a mix of benefits and drawbacks that are important to consider for installations in New Zealand.

Advantages of Coaxial Cable:

• Cost-Effective: Coaxial cables are generally inexpensive, making them widely used for many applications in New Zealand.
• Easy Installation: A coax cable is relatively easy to install and wire, simplifying setup in homes and businesses across New Zealand.
• Durable: The plastic outer jacket of a coaxial cable protects its internal components, improving durability and making them suitable for long-lasting installations in New Zealand's varied environments.
• EMI Resistance: A coaxial cable works by offering good resistance to electromagnetic interference (EMI), ensuring a clean signal, which is particularly important in areas with potential interference, such as near power lines, radio transmitters, or other electronic equipment.
• Signal Containment: The electromagnetic field carrying the signal is contained between the inner and outer conductors. This allows coaxial cables to be installed near metal objects without signal loss, crucial in industries like telecommunications, where cables often run through crowded conduits or near other equipment.

Disadvantages of Coaxial Cable:

• Single Point of Failure: A major disadvantage of a coax cable is that a single cable failure can disrupt an entire network segment. This is something to consider when designing networks in New Zealand, especially where reliability is critical. This can impact what coaxial cables are used for in mission-critical applications.
• Limited Bandwidth: Compared to newer technologies, coaxial cable has a limited bandwidth. While sufficient for many applications, it may not be ideal for very high data transfer rates in modern, high-bandwidth environments.

Coaxial cables come in various types, each designed for specific applications across New Zealand. Generally, coaxial cables are categorized by their impedance, measured in Ohms (Ω). 75 Ohm cables are typically used for video signals, while 50 Ohm cables are more common for data and wireless communications. Impedance refers to the cable's resistance to the flow of electrical energy.

What is a RF Coaxial Cable?

RF coaxial cables are specifically designed to carry radio frequency signals. In New Zealand, they are commonly used as the standard input cable for televisions, featuring a single pin connector that plugs into the RF input.

What is a RG Coaxial Cable?

"RG" stands for "Radio Guide," a designation that originated in military specifications. In New Zealand, various types of RG-rated coaxial cables are used for different purposes, such as connecting TV decoders to satellite dishes, or distributing UHF signals within a building.

RF vs RG Coaxial cable

RF coaxial cable describes the use of a coaxial cable: transmitting radio frequency signals (like TV broadcasts or Wi-Fi). On the other hand, RG coaxial cable describes a specific type of coaxial cable, categorised by its construction and impedance (e.g., RG-6, RG-59).

An RF cable can be an RG cable (like RG-6 for TV), but not all RG cables carry RF signals. Some might be used for other purposes, such as CCTV.

What is a RG-6 coax cable?

RG-6 cables have larger conductors, so they provide better signal quality. They have thicker dielectric insulation and are made with a different kind of shielding, allowing them to handle GHz level signals more effectively. As this type of cable is thin, it can also be easily installed in walls or ceilings.

What is a RG-59 coax cable?

A common cable in domestic settings, RG-59 cable is similar to the RG-6, but it has an even thinner centre conductor. This makes it a good choice for short runs and low-frequency transmissions.

What is a RG-11 coax cable?

RG-11 cable is easily identifiable as it’s thicker than other types of coaxial cable, which can make it more difficult to work with. However, it offers a lower attenuation level than RG-6 or RG-59, meaning it can carry data for longer distances.

While various sizes exist, RG-6 is the most commonly used coaxial cable size in New Zealand for modern applications like digital television and cable internet. Its balance of performance and ease of installation makes it a versatile choice for residential and some commercial uses.

Other sizes, while less prevalent, still have their niche applications.

|<br>Coaxial Cable Type<br>|<br>Outside Diameter (Metric)<br>|<br>Outside Diameter (Imperial)<br>| |-|-|-| |<br>RG-58<br>|<br>4.95mm<br>|<br>0.195"<br>| |<br>RG-59<br>|<br>6.15mm<br>|<br>0.242"<br>| |<br>RG-6<br>|<br>6.90mm<br>|<br>0.275"<br>| |<br>RG-62<br>|<br>6.15mm<br>|<br>0.242"<br>| |<br>RG-11<br>|<br>10.30mm<br>|<br>0.405"<br>| |<br>RG-12<br>|<br>14.10mm<br>|<br>0.555"<br>| |<br>RG-213<br>|<br>10.30mm<br>|<br>0.405"<br>|

Coaxial cables are versatile and find application in a variety of signal transmission scenarios across New Zealand. They are generally used to transport RF signals, which can include anything from the relatively low frequencies of analog television to the much higher frequencies used for digital TV, internet, and other data transmissions. Here are some of the ways coax cables are used, and which types are best for the job:

When coaxial cable lines are produced, they only provide one signal to power a singular device. This can be problematic for residential and industrial applications across New Zealand if there’s more than one device that requires a signal. 

In this case, coaxial splitters are used when there’s more than one device that 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. For example, in telecommunications infrastructure, splitters can distribute signals from a single coaxial cable to multiple antennas or receivers.

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.

In New Zealand, you might find coaxial ports on equipment like radio transmitters, spectrum analyzers, and oscilloscopes. These ports provide a standardised connection point for coaxial cables, ensuring reliable signal transfer for testing, measurement, and communication purposes.

Coaxial cable connectors are used to connect coax cables to other devices and maintain the cable’s shielding.

They come in two main types: male (with a protruding pin) and female (with a recessed hole). Here are some of the most common coax cable connector types and their applications, including examples relevant to New Zealand: