NationMaster - Encyclopedia: Propagation constant

For an electromagnetic field mode varying sinusoidally with time at a given frequency, the propagation constant is the logarithmic rate of change, with respect to distance in a given direction, of the complex amplitude of any field component. The electromagnetic field is a physical field that is produced by electrically charged objects and which affects the behaviour of charged objects in the vicinity of the field. ... For other types of mode, see mode. ... Look up time in Wiktionary, the free dictionary. ... For other uses, see Frequency (disambiguation). ...

The propagation constant, γ, is a complex quantity given by Wave propagation refers to the ways waves travel through a medium (waveguide). ...

where

α, the real part, is the attenuation constant

β, the imaginary part, is the phase constant

i =

Source: Federal Standard 1037C. In telecommunication, the term attenuation constant has the following meanings: 1. ... In electromagnetic theory, the phase constant is one component of the propagation constant for a plane wave. ... Federal Standard 1037C, entitled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ...

As input and output impedences are equal under z_o termination ie, z_o termination = V₁/I₁ = V₂/(-I₂)

 V₁/V₂ = I₁/I₂ = e^γ

where γ is a complex number and is defined as

 γ = α+i β

where

α, the real part, is the attenuation constant

β, the imaginary part, is the phase constant

For 'n' number of sections cascaded' with all of them having the same z_o value' the ratio of currents can be written as In telecommunication, the term attenuation constant has the following meanings: 1. ... In electromagnetic theory, the phase constant is one component of the propagation constant for a plane wave. ...

(I ₁/ -I ₂) × (-I ₂ / -I ₃) × ..... × (-I _n-1 / -I _n) = (I ₁ / -I _n)

=> e^γ₁ × e^γ₂ × ... × = e^γ

The over all propagation constant γ = γ₁+γ₂+....+γ_n

Categories: Physical quantity | Science stubs

Results from FactBites:

Constant folding - Wikipedia, the free encyclopedia (607 words)
	A more advanced form of constant propagation known as sparse conditional constant propagation may be utilized to simultaneously remove dead code and more accurately propagate constants.
	Constant folding can be done in a compiler's front end on the IR tree that represents the high-level source language, before it is translated into three-address code, or in the back end, as an adjunct to constant propagation.
	Constant propagation can also cause conditional branches to simplify to one or more unconditional statements, when the conditional expression can be evaluated to true or false at compile time to determine the only possible outcome.

Constant propagation - definition of Constant propagation in Encyclopedia (153 words)
	That is, known functions of known constants are constants, and are recognised as such.
	Constant propagation can easily be implemented on SSA form as published by Wegman and Zadeck in 1991.
	Constant propagation is not to be confused with constant folding, which is implemented in the front-end.

More results at FactBites »

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