Types of Coaxial Cables and How they are specified

Before learning the types of coaxial cable let’s first understand the coaxial cables and its functioning. Coaxial cables are the form of an electrical cable that includes an inner conductor covered by a concentric conducting shield, that are separated by a dielectric. In simple words it is a system that comprises the inner conductor and outer shield sharing a geometric axis separated by an insulating material to transmit electricity. It can carry high-frequency electrical signals with low losses. Its design is based on physical size, frequency performance, attenuation, power handling capabilities, flexibility, strength, and cost. It is most commonly used in telephone trunk lines, broadband internet networking cables, high-speed computer databases, cable TV connections, etc.

Different types of coaxial cables:

The standard flexible coaxial cable is composed of the outer plastic sheath, woven copper shield, inner dielectric insulator, and copper core. Although there are different types of coaxial cables based on various parameters like construction, application, layer pattern, the material used, etc. Let us study these common types of coaxial cables mentioned below -
1. Hard-line coaxial cable - It is made up of round copper, silver, or gold tubing or a combination of such metals as a shield. The center conductor is generally made up of solid copper or copper-plated aluminum. Dielectric is usually in the form of polyethylene foam, air or pressurized gas as nitrogen, etc. They usually have a larger diameter. The gas-filled hard-lines are mainly used for TV or radio broadcasting, military transmitters, amateur radio applications.

Hard-line coaxial cable

2. Radiating coaxial cable - It is also known as a leaky feeder. It is used as a communication system that is used in underground mining or other tunnel environments. It is designed to radiate something that coaxial cable is unable to do. It works as an extended antenna that can transmit and receive the radio waves through the cable. It also allows for two-way mobile communication. A few of its common applications include mining, underground railways, industrial buildings, etc.

Radiating coaxial cable

3. Formal coaxial cable - It is also known as the RG-6 type of cable. It is used in both residential and commercial applications. It can be coupled  with various cable designs that differ based on various characteristics like shielding, center composition, jacket type, etc. It is typically used for cable TV distribution coax to route the TV signals.

Formal coaxial cable

4. Semi-rigid coaxial cable - It consists of a metal tube made up of copper outer sheath. They are stand-alone microwave components. They have a wide frequency range up to 65 GHz. They can form a shape and retain it for a longer time. They are phase stable. Also, this cable has low passive inter-modulation. It is the most preferred cable type for its broad frequency capabilities, reliable electrical performance, and phase stability.

Semi-rigid coaxial cable

5. Rigid coaxial cable - It is made up of two copper tubes placed in concentric patterns every other meter using supports. It cannot be bent so often it needs an elbow. They are connected with the help of connectors. They are commonly used indoors for interconnection between high power transmission and other RF components. Sometimes it comes with specialized braces and springs. These springs help in differential expansion and contraction of inner and outer copper lubes used in the transmission line run.

6. Twin axial cable - It comes with 2 inner conductors instead of one. It is suitable for very short-range high-speed differential signaling applications. It has a reduced cable loss, higher protection from ground loops and captive fields, and lower low-frequency magnetic noise. They are commonly used for low frequency digital and video applications, high-performance computing clusters, data center networks and storage, server applications.

Twin axial cable

7. Triaxial cable - It is also known as Triax. It is a form of an electric cable with an addition of an extra layer of insulation and second conducting sheath. It offers greater bandwidth and cuts off the interference unlike coax, and reduction in cable losses and cable loading. Some of its common applications include television production as connecting cable between camera and camera control unit, taking precision low current measurements.

 Triaxial cable

Few of the other types of coaxial cables includes -

  1. Coaxial ribbon cable assemblies - They are flexible, have low loss, semi-rigid, and conformable. They can be configured with any connectors. A few of its benefits are high data transfer capacity, support for different stations, and low error rates.
  2. Micro coaxial cable - They are used in a wide array of precision medical products and cabling applications. They are suitable for confined spaces, where high reliability, high sensitivity, outstanding signal, capacitance, and impedance are crucial characteristics.
  3. High-temperature coaxial cable H- They are used in a wide variety of configurations to suit every harsh environment application. The temperature range for the majority of the coaxial cable is -55/+200 degree and for triaxial cable -55/+150 degree.
  4. Water-cooled coaxial cable - It is used for conductive heaters and hardening equipment as well as welding processes. It is designed with an electrically neutral and flexible center hose as a carrier for the braid of copper wires.

How coaxial cables are specified:

  1. Attenuation (Insertion loss) - It signifies loss of power. It is usually measured in dB loss per length of cable and  increases proportionally as frequency increases.
  2. Bend radius - It is the measure of cable radius that can bend without any adverse effects.
  3. Center conductor - It is a solid wire form material present in the middle of coaxial cable.
  4. Coaxial Adapter - It is used to change one connector type to another.
  5. Coaxial connector - The interconnection device found at each end of the coaxial cable assembly.
  6. Electromagnetic Interference - It is a type of electromagnetic energy that disrupts electric signals.
  7. Frequency - The number of times a periodic action occurs in a second. It is measured in hertz.
  8. Impedance - It is a measurement of resistance to the flow of current. It is measured in ohms.
  9. Jacket material - Type of material used as a protective outer layer of cable.
  10. The rated temperature for the cable.

Conclusion:

To minimize  the interference and troubleshooting problems in coaxial cables,  the user must check the construction and design of these cables. Along with that, users need to verify the material used, filament, center conductor, proper installation of connectors, and attachment of shield. The issues like signal leakage, ground loops, noise, transformer effect, and common mode current and radiation can be rejected or reduced by selecting the correct type of coaxial cable that is suitable for the working environment and application. Every type of coaxial cable has its benefits that users should bear in mind  before assembling them in their system.