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What Are Coaxial Cables?

What Are Coaxial Cables?

Coaxial Cable: The Backbone of RF Systems

Coaxial cables or coax cables have been around since the 1880s. They are a type of transmission line used to transmit radio frequency (RF) signals from one point to another with low signal loss.

Common coaxial cable applications include: 

  • Cable Television
  • Radio Equipment
  • Cellular Signal Boosters
  • Broadband Modems, Routers, and Gateways
  • Antennas
  • Other RF Applications

They’re the backbone behind movies playing on your TV, online gaming, improved cellular reception, and more.

However, coax cables are not one size fits all. For optimal performance, the right cable is needed for each application. Here is all you need to know about coax cables to find the best one for your needs and achieve the best setup.

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How Does Coaxial Cable Work?

Coaxial cables relay signals between RF transmitters and receivers. The construction of coax cables allows the transmission of signals with minimal interference and signal loss over long distances.

At the core, we have the center conductor, made of solid or braided copper. It carries the signal from point a to point b as an alternating current. A mesh outer conductive shield, and in some cases a solid metal shield, ensures the signal travels intact through the cable. It minimizes signal leakage as well as electromagnetic interference. The term “coaxial” actually comes from the two conductors sharing the same geometric axis.

Both conductors generate a current. A dielectric shield insulates the core and separates the inner and outer conductors. This ensures they do not come in contact with each other and cancel each other out. The separation between the two conductors is vital for the transmission of the strongest signal. Changes will reduce performance. Some cables feature multiple shields to further minimize interference and signal loss.

Air-dielectric coax cables do not have a traditional dielectric shield that separates the conductors. The conductors are separated by air and plastic spacers.

All components are wrapped and protected in an insulating jacket.

Each end of the cable is terminated with coaxial connectors. They connect to the RF transmitter and receiver.

Here is an image of the different layers of coaxial cables:



What is Coaxial Cable Loss?

No coaxial cable is perfect. They all have loss or attenuation, measured in decibels (dB). Loss refers to the decrease in power of a signal as it travels the length of the cable. The amount of loss varies across cable length and frequencies. Some cables have less loss than others.

The main contributors to coax cable attenuation are:

  • Resistive Loss: Conductors have some resistance to the flow of electrical energy passing through them. This results in some electrical energy being lost as heat. The longer the cable, the more heat is lost, leading to greater attenuation.

  • Dielectric Loss: Represents electrical signals being lost as heat within the dielectric insulator, hence the name. This occurs when the dielectric insulator absorbs energy from the electromagnetic field developed between the core and outer conductor. This type of loss is independent of coaxial cable size. It increases linearly with frequency, meaning higher frequencies experience more dielectric loss than lower frequencies.

  • Radiated Loss: Occurs when the electrical energy passing through the cable leaks out. Not only does this weaken the transmitted electrical energy, but it can also introduce signal interference. Radiated loss is typically much less than resistive and dielectric, making it the least concerning type of loss. However, a poorly constructed or damaged outer conductor can generate a high radiated loss.

Other things that can add attenuation to your setup are the introduction of adapters, filters, and other similar components.

To minimize signal loss, we recommend you use the shortest length of cable possible for your application.

What is Coaxial Cable Impedance?

Impedance, measured in Ohms, refers to the value of electrical resistance in alternating current.

Without getting too technical, most cables have an impedance of either 50 Ohms or 75 Ohms.

  • 50 Ohm cables prioritize power transmission and signal quality. They are the preferred option for high-power handling applications, like TV transmitters, broadcasting radios, commercial cellular boosters, etc. They are predominantly installed in commercial spaces.

  • 75 Ohm cables prioritize low attenuation and signal quality. More affordable, they are the preferred choice for applications that do not require high power handling. They are commonly used in residential buildings with cable TV, home cellular boosters, internet routers, audio, etc.

It’s vital to keep a consistent impedance throughout the cable and setup. Mixing and matching impedance causes signal reflection, decreasing strengths and increasing loss. It's best to use 50 Ohm cables with 50 Ohm systems and 75 Ohm cables with 75 Ohm systems.

If your setup requires in-line accessories like adapters, surge protectors, filters, and such, it’s recommended impedance matches across the board to avoid unnecessary attenuation.

What Are the Different Types of Coaxial Cables?

While all coax cables serve the same purpose, there are different types of coaxial cables available to cater to a variety of needs. Here is our selection of Bolton Technical coax cables:

Bolton RG6 Coax Cable

Bolton RG6 coaxial cable is a popular 75 Ohm cable for home and office applications. They are usually made for indoor use. However, ours can also be used outdoors.

Many buildings are wired with this type of cable. It’s commonly used in radio antennas, RF systems, cable televisions, HDTV, internet, and the like. Thin and flexible, it’s easy to install in complicated layouts without compromising performance.

Bolton 200 Coax Cable (LMR®200 Spec Equivalent)

Bolton 200 is a 50 Ohm, low loss, flexible cable designed for indoor or outdoor use. Popular applications include short antenna feeder runs and those requiring easily routed cable (i.e. WLL, GPS, WISP, Mobile Antennas).

Specifications are comparable to RG-58 and RG-142 cables but with much higher electrical performance. This makes it a suitable upgrade for those cable types.

Bolton 240 Coax Cable (LMR®240 Spec Equivalent)

Bolton 240 coaxial cables have an impedance of 50 Ohms and offer the lowest loss of any flexible coax cable. Attenuation is comparable to more rigid, commercial-grade cables.

Like RG6, this cable can be easily maneuvered around walls and ceilings without damaging any components, ensuring great signal transmission. They can be installed indoors and outdoors. It’s ideal for jumper assemblies in wireless communications systems, short antenna feeder runs, GPS, WLAN, WISP, WiMAX, SCADA, and mobile antennas.

Bolton 400 Coax Cable (LMR®400 Spec Equivalent)

Bolton 400 carries high-frequency RF signals for wireless communication systems and other antenna applications. It has an impedance of 50 Ohms.

Originally, this type of cable was made to replace lower-quality coax like the RG8. Its construction allows for ultra-low signal loss across long distances. Much thicker, it’s less flexible than the previously mentioned LMR® spec cables. It’s commonly used for commercial applications but may also be integrated into residential buildings.

Bolton 600 Coax Cable (LMR®600 Spec Equivalent)

Bolton 600, also known as Half-Inch, is one of the highest-grade 50 Ohm, indoor and outdoor-rated coax cables. Compared to the other LMR® spec options, it offers the lowest attenuation across long distances.

This cable is often used for RF communication systems and antenna applications in commercial settings needing long cable runs. It transmits a higher-quality signal than the Bolton 400. Much thicker and sturdier, it’s more challenging to install.

Looking for Cable?

Bolton Technical, a trusted partner, is the manufacture of the highest quality coax cables with low loss. Undergone extensive testing, they are guaranteed to exceed expectations. You can shop Bolton cables here or view our entire selection of coaxial cables here.

For any questions regarding coaxial cables, don’t hesitate to call us at 1-800-638-6336 or email us at sales@signalboosterscanada.ca. We’re here to help!

Alejandra Jasso
Apr 25th 2024

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