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  • Writer's pictureEthan Barr

Coaxial Cable - Understand the basic

Coaxial cables are used to carry Radio Frequency (RF) also called signals. The transmission line or signal runs in the space between the inner and outer conductors.

The shield on a coaxial cable has a very important task: it is there to reduce signal loss by creating a barrier between the signals that run in the cable and outside electromagnetic interferences.

Many times, we run coaxial cables along a conduit that also contains electrical wires and the like. Having a high-quality, low-loss cable with good shielding is paramount to optimize the performance of the cable.

In our field, there are two types of dB values that we need to know and be aware of: one is called dB loss, and the other is called dB gain. Just as it sounds, one represents the losses. For example, if a certain length of coaxial cable has a 3dB loss, that means at the base of the antenna, some of the transmitted power has been lost.

And vice versa, dB gain means that now the signal has been passed through a good antenna or an amplifier and has gained power.

Every coaxial cable has dB loss, but the value differs based on various parameters. The general rule is the thicker the cable, the less signal loss you will experience.

Take this chart, for instance:

A thinner RG-58CU cable, (RG) stands for Radio grade of 100 feet long, loses 6.1 dB, while a thicker RG-213 of a similar length only loses 2.7 dB.

By using RG-213 cable instead of the RG-58CU, your radio transmitter will now lose only half of the power you originally lost when you used the RG-58CU cable. Therefore, now more of it will reach the antenna!

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