Coaxial cables, usually shortened to “coax” cables, are a type of heavy-duty electrical cable used in a variety of radiofrequency (RF) signal transmission applications.
These cables are all around us and have been so since the start of the 20th century. They have important applications in telephone, cable, and internet, which makes them ubiquitous in people’s homes and workplaces.
The technology of coax cables is continuously evolving. As such, it can be difficult to remember each type of coax cable that exists. Especially considering the versatility of these cables, there are many applications they are used in.
Below, we’ve outlined the main types of coax cables, along with their uses. But first, let’s see just what a coax cable is.
What Is a Coax Cable?
As you may already know, the purpose of coaxial cables is to transmit electrical signals from one device, component, or system to another. Coax cables are distinctly recognizable due to their heavy construction.
In addition, this also makes them one of the most durable types of cables used in radio frequency transmission operations. The name “coaxial” is derived from the common axis of the cable’s two conductors.
How Coaxial Cables Work
In order to understand how coax cables work, we must first be acquainted with its four different layers.
- A center conductor that is typically made from copper. This conductor transmits video and data.
- Surrounding the center conductor is a plastic dielectric insulator. This prevents signal loss and facilitates the reduction of EMI. It also provides insulation and creates distance between the core conductor and external layers.
- A copper braided mesh shields the cable from EMI and radio transmissions.
- The plastic external prevents damage to the internal layers.
The Make-Up of a Coax Cable
The primary reason behind the success of the coax cable is its shielded and layered design. Consider the regular electrical cable, inside which one or more wires are responsible for passing electrical currents. In contrast, a coax cable passes radio frequency (RF) signals, which manifests as transverse electromagnetic waves.
Inside a coaxial cable is an inner conductor cable made of copper. This cable is surrounded by a lightweight plastic dielectric layer or an insulating agent. The insulator, in turn, is shielded by a lightweight braided mesh. Moreover, the whole group of layers is covered by a protective external insulating jacket.
Additionally, this very design is what allows a coax cable to perform successfully without interference from external electromagnetic fields. Not only that, but environmental stressors are also kept at bay. The result is a highly durable transmission cable capable of passing signals of high frequency at low loss.
A coax cable offers a transmission speed of 10 megabits per second. They also have a transmission capacity that’s 80 times higher than twisted-pair cables.
The different parts of a coaxial cable are outlined below.
- Center conductor: Usually made from copper-clad steel.
- Center Conductor bond: In which the use of clean stripping polymer prevents moisture migration.
- Dielectric: Made from polyethylene for a high-VP closed-cell foam.
- First outer conductor: An aluminum-polymer-aluminum tape is bonded with the dielectric core to create a shield.
- Second outer conductor: A second aluminum-polymer-aluminum tape is used in the construction of tri-shields and quad-shields. This facilitates the isolation of the HF shield before and after flexure.
- Third outer conductor: Same application as the
- Fourth outer conductor: In an environment of high RF noise, another 34/36 AWG aluminum braid is used in the construction of quad-shields to facilitate LF shield isolation.
- Protectant: The protectant must be corrosion resistant.
- Indoor and aerial: Prevents moisture migration using a non-drip material.
- Underground: A flowing compound that can seal ruptures in the jacket.
- Jacket: Constructed from either PE or PVC, a UV stable outer jacket protects the conductor core during and after installation.
- Integral messenger: A support member made from galvanized carbon steel wire connected via a separable web to the cable.
Coax Cable Types and Their Uses
Without further ado, let’s jump into the different types of coax cables that are available. We’ll also be covering the practical uses of each type, so you can choose the right one in setting up your network.
1. Hard-Line Coaxial Cable
The most commonly used type of coaxial cable, hard-line coaxial cables are preferred in applications that require a high signal strength. These cables usually measure around 0.5 inches to 1.75 in thickness, which makes them larger in diameter than other coaxial cable types.
They have a center conductor made of materials like silver, copper, aluminum, or steel. Some hard-line cables integrate pressurized nitrogen to inhibit moisture intrusion and arcing.
Hard-line coaxial cables are typically used in the transmission of cable TV. One of these cables has the capacity to transmit hundreds of cable TV channels. Moreover, they are also used in telephone and internet lines.
If your office or apartment building is fairly medium-sized, a hardline coaxial cable can be depended upon to do the job of delivering internet and telephone connectivity.
2. RG-6 Coaxial Cable
The RG-6 is another coaxial cable that is widely found in our surroundings. The “RG” in its name stands for “radio guide,” while the number refers to the cable’s diameter. In this case, the “6” indicates that the cable has a diameter of .06. RG-6 cables are also called RF (radio frequency) cables.
One of the reasons the RG-6 is so popular is because it tends to have larger conductors. This facilitates improved signal quality.
Because they have unique shielding and are equipped with thicker dielectric insulation, they are better able to accommodate GHz level signals. Furthermore, some RG-6 cables are waterproof. Because of its thinness, the RG-6 is easy to install in ceilings and walls.
That’s what makes this cable ideal for transmitting cable TV and broadband internet, and also the reason why they are so easily found in people’s homes. The RG-6 is the perfect cable to use in entertainment systems both in households and commercial institutions.
3. RG-11 Coaxial Cable
Similar to the RG-6, the RG-11 is a cable that has a 75-ohm impedance. It’s thicker than the RG-6, however, and is used most commonly for applications in satellite, TV, or cable TV. Although it’s less flexible than the RG-6, it provides the benefit of lower loss.
More so, the result is that a higher signal is delivered to the receiver. Thus, RG-11 coaxial cables are ideal for use in long-distance applications. They’re also great for HDTV connection as they have a higher gauge.
4. RG-59 Coaxial Cable
Similar to the RG-6, the RG-59 is found in many domestic video applications. It’s characterized by a relatively thinner center conductor, which allows it to be more efficient for low-frequency transmissions and short runs.
5. Tri-axial Cable
The tri-axial coaxial cable (also called “Triax”) is characterized by an additional shield in the form of a copper braid. Because this braid is grounded, it protects the cable’s inner conductive elements from capacitive field noise and ground loop currents.
Furthermore, since the triaxial cable offers higher bandwidth and interference rejection, it’s ideal for use in applications where strong electromagnetic forces may interfere.
Moreover, it efficiently reduces cable loading and cable losses. The most commonly seen use of triaxial cable is on cable TV. It is also used to connect cameras to their CCU (camera control unit).
6. Semi-Rigid Coaxial Cable
As the name suggests, the semi-rigid coaxial cable is less flexible. This is due to the fact that its shield is typically made from harder metals.
Taking this into consideration, you can imagine why such cables are typically preferred in situations where the cable can be laid straight without needing to be curved or bent. After it has been formed initially, this type of cable cannot be flexed or reformed.
7. Flexible Coaxial Cable
In contrast to the semi-rigid coaxial cable, the flexible variation can–as its name implies–be flexed or moved according to the needs of the situation. Such cables come with an inner conductor made of metal, which is in turn surrounded by a dielectric of flexible polymer. On top of this is a protective external jacket.
The flexible coaxial cable should be used in situations where you might need to increase its flexibility. In that case, you have the option of switching the metal core conductor to a solid-wire stranded design. Meanwhile, a dielectric of PE foam can be substituted for the existing polymer dielectric.
Flexible coaxial cables are most commonly seen in applications relating to cable TV or home video equipment.
8. Formable Coaxial Cable
Not to be confused with the flexible coaxial cable, the formable coaxial cable is a good alternative to semi-rigid coax cables. These cables have a tough outer sheath made of flexible metal instead of rigid copper. This metal can be formed or reshaped by hand (hence the name) to fit the needs of the situation.
Formable coax is used occasionally in prototype applications to layout cable placement design. Once set, the design is altered to utilize the semi-rigid coaxial cable.
9. Rigid Coaxial Cable
Also called rigid line, the rigid coaxial cable is actually a misnomer as it’s quite flexible. This is because rigid coaxial cables are usually produced and sold in fixed-length flanged straight sections.
45 or 90-degree elbows may be used to join transmission line sections together according to what the situation demands.
In terms of practical usage, the rigid line coaxial cable is typically used for indoor purposes. They’re ideal for powerful connections in FM and TV broadcasting systems. The construction of a rigid coaxial cable features a copper inner conductor with the external conductor being made from aluminum or copper.
10. Twinaxial Cable
Similar to the coaxial cable, the twinaxial cable is different in the sense that its center has two individual conductor wires (instead of one). Twinaxial cables offer reduced cable loss and more efficient protection from capacitive fields and ground loops.
Low-frequency magnetic noise reduction can also be accredited to twinaxial cables. Twinaxial cables are the most suitable option for low-frequency video and digital applications.
The persisting popularity of coax cables is owed not only to their durability and strength but other factors as well. They are affordable and easy to install. Furthermore, expanding them is easy as well. And of course, there’s the high EMI resistance and speed capacity of 10Mbps.
Hopefully, our discussion of each type of coax cable has enlightened you. We wish you good luck with building your network!