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An electromagnetic wave propagating in the +z-direction is conventionally described by the equation: (,) = [()], where E 0 is a vector in the x-y plane, with the units of an electric field (the vector is in general a complex vector, to allow for all possible polarizations and phases);
The input impedance of an infinite line is equal to the characteristic impedance since the transmitted wave is never reflected back from the end. Equivalently: The characteristic impedance of a line is that impedance which, when terminating an arbitrary length of line at its output, produces an input impedance of equal value. This is so because ...
In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight , lead attenuates X-rays , and water and air attenuate both light and sound at variable attenuation rates.
To avoid reflections, the impedance of two media must match. On the other hand, even if the real part of the refractive index is the same, but one has a large absorption coefficient, the impedance mismatch will make the interface highly reflective. The wave impedance is given by = ()
The most important effect of skin effect on the impedance of a single wire is the increase of the wire's resistance, and consequent losses. The effective resistance due to a current confined near the surface of a large conductor (much thicker than δ ) can be solved as if the current flowed uniformly through a layer of thickness δ based on the ...
The Q factor is a parameter that describes the resonance behavior of an underdamped harmonic oscillator (resonator). Sinusoidally driven resonators having higher Q factors resonate with greater amplitudes (at the resonant frequency) but have a smaller range of frequencies around that frequency for which they resonate; the range of frequencies for which the oscillator resonates is called the ...
Specific acoustic impedance z is an intensive property of a particular medium (e.g., the z of air or water can be specified); on the other hand, acoustic impedance Z is an extensive property of a particular medium and geometry (e.g., the Z of a particular duct filled with air can be specified). [citation needed]
Impedance matching is important when components of an electric circuit are connected (waveguide to antenna for example): The impedance ratio determines how much of the wave is transmitted forward and how much is reflected. In connecting a waveguide to an antenna a complete transmission is usually required, so an effort is made to match their ...