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Attenuation

Physics: Cambridge International A Level, topic 10.1.3

Attenuation

Attenuation is the loss of strength of a signal as it travels through materials.

Signal attenuation

Signal attenuation

  • Attenuation is the loss of strength of a signal as it travels through materials.
  • This occurs as the wave's energy is gradually absorbed into its surroundings.
  • Attenuation is measured in decibels or dB.
Calculating decibels

Calculating decibels

  • The attenuation of a signal before and after transmission is equal to:
  • number of dB=10log10(P1P2)\text{number of }dB = 10log_{10}\left(\frac{P_1}{P_2}\right)
  • Where log10log_{10} is the logarithmic function of base ten, which you can work out on any scientific calculator.
  • P1P_1 and P2P_2 stand for the power of the signal before and after transmission, which can be calculated using the equation:
  • P=IVP=IV
  • If attenuation has taken place, the number of decibels will be negative.

Test yourself on Attenuation

  • What is the attenuation of a wave that has a power of 5 μW at the source and a power of 2 μW at the receiver?

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