What is attenuation in an electrical system?

Attenuation in an electrical system is the loss or reduction in the amplitude or strength of a signal as it passes along its length. As the signal travels through the copper wire conductor some of the signal will be absorbed.

Attenuation is a result of resistance in the conductor and associated dielectric losses which is exaggerated by longer run lengths and higher frequency signals. By improving the dielectric properties of the insulation and increasing the conductor size it will reduce the attenuation.

Attenuation is expressed in units called decibels (dBs). If the attenuation is related to signal power then the formula is given by:

A (power) = 10 log10 ( Ps / Pd )

Ps = power at source

Pd = power at destination


If Attenuation is expressed as Voltage, the attenuation the formula becomes:

A (Voltage) = 20 log10 ( Vs / Vd )

Vs = voltage at source

Vd = voltage at destination

Attenuation is often expressed in dBs per foot, meter, kilometre etc. The lower the attenuation figure over any given measurement of distance, the more efficient the cable is. When signals are transmitted over greater distances it may be necessary to include repeaters to boost the signal strength and reduce the effect of attenuation.

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