Whenever you hear of a coaxial cable, think of the cord that connects your TV to the aerial above. But there are other types of coax cables in video, internet, CCTV, and HDTV signal transmissions.
What exactly is the reason behind its popularity in these applications? Find out that from this coaxial cable guide that looks into its structure, features, and types, among other vital details.
We’ll also explore some of the alternatives to these cables. Take a look.
Table of Contents
- What is a Coaxial Cable?
- How do Coaxial Cables Work?
- Types of Coaxial Cables
- Common Coaxial Cable Sizes
- Uses of Coaxial Cables
- Coaxial Cable Advantages and Disadvantages
- Which Is Better: Coaxial Cable or Fiber Optic Cable?
- Important Coaxial Cable Features to Consider Before You Buy
What is a Coaxial Cable?
It’s an electrical cable featuring a single copper conductor in the innermost layer covered by an insulate and a braided metal mesh. Its role is to transmit radio frequency signals from one point to another.
The inner layer deals with the signal transmission, while the insulator and the metal mesh protect the conductor from signal interference.
The layers are also responsible for preventing the impact of crosstalk/noise signals. Hence, even when you have coaxial cables next to each other, there cannot be signal corruption thanks to the insulation.
A plastic layer that further protects the conductor is on the outer level of the coaxial cable.
How do Coaxial Cables Work?
Coaxial Cable Structure.
The fundamental operation of the coaxial cable is anchored on its structure. At the cable’s center is a copper conductor via which video and data travel. Next, a dielectric plastic insulator protects the inner cable during the transmission.
Above the insulator is a braided mesh, arguably the most critical insulator. It shields the copper layer from electromagnetic interference (EMI) from surrounding conductors. Finally, a plastic layer covers the entire cable.
Hence, the cable layout means the center part is responsible for signal transmission. The other layers enhance this process by preventing signal loss. In their absence, attenuation loss would happen, especially if there’s surrounding EMI.
Types of Coaxial Cables
A 50-ohm coaxial cable.
There are seven main coaxial cable types, and we’ll cover them in detail below.
Hardline Coaxial Cable
It’s the cable with the largest diameter of all the types. It also features a copper or silver interior.
Semi-Rigid Coaxial Cable
It is not entirely rigid thanks to its makeup materials, which comprise an outer sheath of solid copper. The Polytetrafluoroethylene dielectric is what is responsible for the semi-rigid nature.
Formable Coaxial Cable
If you want an alternative to the semi-rigid coaxial cable, go for this type. Rather than a rigid outer copper sheath, this one features a flexible one. It can easily bend around corners without the risk of destroying the insulators.
Flexible Coaxial Cable
As per its name, this cable is essential in transmissions where you’d like to achieve flexibility. The cable’s interior conductor cover makes it possible, which is typically a flexible polymer.
It is not purely a coaxial cable because, as per its name, it features two rather than one conductor at the core. Next to the two conducting components is an outer core and a dielectric layer above it.
If you want a cable for low-frequency transmissions, whether digital or video, choose the twin-axial type. It’s best suited for such applications.
It is also called the Triax because of its additional copper braid layer that shields against noise and interference. The cable is ideal for applications that require additional bandwidth.
Rigid Coaxial Cable
As its name suggests, the cable is rigid and features dual copper tubes with disk insulators and PTFE supports at the ends. You cannot bend the cable, but it is still crucial in broadcasting systems and TV applications.
Common Coaxial Cable Sizes
There are two primary coaxial cable sizes, namely RG-6 and RG-11. The RG prefix before the dash means they are radio-grade cables, thus perfect for radio frequency transmissions.
Notably, the most common cable in typical applications is the RG-6 cable. It’s ideal for uses with a 150 feet range. On the other hand, RG-11 is perfect for applications involving a drop longer than 150 feet.
Uses of Coaxial Cables
A coaxial cable in 3D.
Coaxial cables find widespread application in Ethernet LANs and other uses that involve data transmission. Below are the typical coaxial cable applications:
RG-6 cables are responsible for transmitting the internet from one point to the other.
CCTV Signal Transmission
Like internet and TV signals, CCTV is also a type of radiofrequency; thus, we use coaxial cables to transmit them. The two coax types for this role include RG-6 cables and RG-59 cables.
Another everyday use of coaxial cables is carrying TV signals. The ideal cable type for this application is the RG-6 coaxial cable with the 75 Ohm specification.
The universal-use RG-6 coaxial cable guarantees excellent digital signals in video transmission applications. But for the ultimate lossless transmission, especially when dealing with video signals, go for the RG-59.
High-definition transmissions require a special cable with better features than the typical coax. So, we advise you to go for the RG-11, primarily because of its relatively large space for signal transmission.
Coaxial Cable Advantages and Disadvantages
Coaxial cables cross-section.
Upsides of Coax Cables
- They have a relatively high bandwidth capacity and are relatively easy to set up.
- The cut-through resistance of coax cables is exemplary. Thus, they are ideal where durability and reliability are necessary.
- They can support multichannel transmissions.
- Also, the cables’ makeup means they have cross-talk, EMI, and noise resistance.
Downsides of Coax Cables
- They are expensive and require expertise in setup, especially given that they need proper grounding to prevent crosstalk.
- The numerous layers of the coax cables mean that they’re pretty bulky to move from one point to another.
- Also, they are prone to hacker attacks. Often, you may have a cable with a “t-joint” that creates a perfect loophole for hackers to access your data.
Which Is Better: Coaxial Cable or Fiber Optic Cable?
Fiber optical cables.
Fiber optic cables fare better than typical coax cables.
- First, fiber optics are ideal for long-distance transmissions and have relatively lesser signal losses than coax cables.
- Fiber cables can also carry more data than coax cables.
But if you’re looking for the cheaper option, go for coax cables, which are much less costly than fiber optics. The setup for coax cables is also relatively easier, and the costs for fiber optics delivered internet are higher than with coax.
Important Coaxial Cable Features to Consider Before You Buy
Inner Structure of a Coaxial Cable.
What are some of the critical considerations you should make when purchasing coaxial cables? Find out below.
Length and Thickness
A long cable may sound like the ideal option when transmitting over long distances. Nonetheless, signal loss is directly proportional to the cable length. You should go for a thicker cable, as an increase in the cross-sectional area decreases signal loss.
So, ideally, choose a cable that is as short yet thick as possible to facilitate excellent transmission.
Coaxial Cable Rating
Coaxial cable manufacturers create different types of cables, each suited to a specific application. Hence, when buying a cable, ensure the type reserved for the use you intend to use it.
Go for the Communications Multipurpose Plenum (CMP) Cable for air space transmission. Their fundamental feature is the ability to release relatively low smoke in case of a fire accident, and they also have fire retardant features.
The alternative is the Communications Multipurpose Riser (CMR) rated cables. They share features with the CMP cables, although their resistance is less profound than CMP’s. You need these cables when running wires between floors.
Finally, we have the Communications Multipurpose (CM) Cable or the PVC cable. It’s the cable for most general-purpose applications and doesn’t have the unique features of the other cable types we’ve covered above.
The dBm is a measure of the cable’s supplied signal strength. Your cable size and features should be commensurate with the signal strength under transmission.
Coaxial Cable Impedance
A perfect coaxial cable should have a relatively low impedance. The impedance is a measure of the cable’s resistance to signal transmission. If it is high, it means that the signal transfer will be complicated.
The best impedance ratings are 50 and 75 ohms, ensuring a perfect balance between excellent transmission and low signal loss.
Specifically, the 50 ohms cable is helpful in high-power applications, while the 75 ohms perfectly fits home and office uses.
Signal distortion is probable when the cable has a high passive intermodulation (PIM). This effect is more profound with an increase in the signal amplitude. Hence, always go for low PIM coaxial cables.
Choose the Ideal Coaxial Cable Connectors
Coaxial cable connector assembly.
A connector is critical as it ensures that the cable’s integrity remains even when it connects to an external device. The main connector types include:
Their name is a short form for Subminiature version B, and they are connectors for cables with unusual connections. They are also widely popular; thus, you’ll find them in numerous telecommunication applications. However, they are not built for rugged working conditions as the type A connectors.
Most Subminiature A connectors are brass, although you may also likely come across steel-made ones.
Their primary standout feature is the ¼ – 36 threaded coupling renowned for its high-performance guarantee in compact connections.
It also comes with a screw design and is the perfect fit for cables with an impedance of 50 Ohms.
They are relatively large and, thus, primarily ideal for use with thick cables. You’ll mostly find them in commercial cables with large sizes.
It’s a mid-size connector common in RG-6/U cable and ideal for residential wiring purposes such as cable modems and satellite TVs. This application means that they are amongst the most popular cable types.
TNC is the short form for Threaded Neill-Concelman; these are connector heads for antenna and mobile phone connections. They’re specialty connectors that can perfectly function in rugged conditions thanks to their waterproof nature.
It’s a 50-ohm connector reserved for mobile equipment connections. It connects to cables with the capacity to transmit up to 2000 MHz. Hence, it is popular in data and cellular device applications and services.
The Amphenol coax connector is the perfect fit head for low-frequency RF uses. They have an impedance of 50 Ohm and are the most common connectors.
You’ll find them in amateur radios, marine VHF and other everyday applications that require a frequency of up to 300 MHz.
As discussed in this guide, coax cables play a fundamental role in radio frequency applications. Their design ensures a limited chance for signal loss and cross-talk.
Further, they are EMI-resistant, which explains their widespread popularity in TV, radio, CCTV, and Internet transmission applications.
Choose the cable specialized for the application you want to use for the best results. Also, you can contact us for any further advice on coaxial cables for your auto-wiring application.