# Attenuation Coefficient

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## attenuation coefficient

[ə‚ten·yə′wā·shən ‚kō·ə′fish·ənt]
(electromagnetism)
The space rate of attenuation of any transmitted electromagnetic radiation.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

## Attenuation Coefficient

(or extinction coefficient), a quantity inverse to the distance at which the radiation flux forming a parallel beam is attenuated as a result of the joint action of the absorption and scattering of light in a medium by a specified factor. When the factor is 10, the coefficient is called the decimal attenuation coefficient, and when the factor is e, it is called the natural attenuation coefficient. The attenuation coefficient is the sum of the absorption coefficient and the scattering coefficient of the medium. These coefficients depend on the set of frequencies v, or wavelengths λ, that characterize the initial flux. The value of the attenuation coefficient for the limiting case of a single frequency v is called the monochromatic attenuation coefficient. Like the absorption and scattering coefficients, the attenuation coefficient can be divided by the volume of the medium or by the mass of the attenuating substance; we shall call these two ratios the volume and mass attenuation coefficients, respectively.

References in periodicals archive ?
From Figure 3, it can be seen that the change rate of attenuation rate of PSV increases first and then decreases with the increase of the polishing cycles.
(3) The degree of development that the rock mass joints have undergone influences the attenuation rate of the PPV, and the PPV attenuation rate is high when the number of joints in the rock mass is high.
Caption: Figure 3: Relationship between fluid viscosity and energy attenuation rate and [T.sub.2] value.
However, the attenuation rate in high frequency is only 20 dB/decade, which cannot reach 40 dB/decade achieved by absolute velocity feedback control system.
The attenuation rate in a particular medium can be defined as the amplitude decay undergone by an elastic wave traveling in this medium, per unit of distance.
The duct attenuation rate ([alpha]) was determined from the insertion loss.
The attenuation rate is dependent on the dielectric permittivity [epsilon], magnetic permeability [mu], and electrical conductivity [sigma] but not on the frequency [omega] (nonfrequency dependent media, but for rock, it is frequency dependent).
Parameter Simulation Resonance frequency 4.77 GHz Return loss 0.34 dB Insertion loss 30.52 dB Q-factor 3.68 Attenuation rate near the resonance 210.42 dB/GHz Table 2.
The attenuation rate of the crystal silicon modules will not exceed 2% within two years nor exceed 20% within 25 years.
This is an attenuation rate of 34 dB [m.sup.-1], assuming that the difference in distance between the source and the two sensors was 20 cm.
The goal of the investigation was to determine an upper attenuation rate, and it's clear that none of the simulated source configurations falls off faster than 20 dB/decade up to about [R.sub.meas]/[R.sub.FF] = 0.3.

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