Ingeniero En Telecomunicaciones
Páginas: 7 (1648 palabras)
Publicado: 11 de diciembre de 2012
Cross Polarization
Cross polarization (sometimes written X-pol, in antenna slang) is the polarization orthogonal to the polarization being discussed. For instance, if the fields from an antenna are meant to be horizontally polarized, the cross-polarization in this case is vertical polarization. If the polarization is Right Hand Circularly Polarized (RHCP), the cross-polarization is Left HandCircularly Polarized (LHCP). See also Polarization.
This term arises because an antenna is never 100% polarized in a single mode (linear, circular, etc). Hence, two radiation patterns of an antenna are sometimes presented, the co-pol (or desired polarization component) radiation pattern and the cross-polarization radiation pattern.
The cross polarization may be specified for an antenna as apower level in negative dB, indicating how many decibels below the desired polarization's power level the x-pol power level is.
Polarización cruzada (a veces escrito X-Pol, en la jerga de antena) es la polarización ortogonal a la polarización que se discute. Por ejemplo, si los campos de una antena están destinados a ser polarizada horizontalmente, la polarización cruzada en este caso es lapolarización vertical. Si la polarización es la mano derecha de polarización circular (RHCP), la polarización cruzada es mano izquierda polarizada circularmente (LHCP). Véase también la polarización.
Este término se debe a que una antena no es 100% polarizada en un solo modo (lineal, circular, etc.) Por lo tanto, dos patrones de radiación de una antena se presentan a veces, la co-pol (o componentedeseado polarización) patrón de radiación y el patrón de radiación de polarización cruzada.
La polarización cruzada se puede especificar para una antena como un nivel de potencia en dB negativos, lo que indica cómo muchos decibelios por debajo del nivel de potencia de la polarización deseada es el nivel de potencia de x-pol.
Brewster's angle
An illustration of the polarization of light which isincident on an interface at Brewster's angle.
Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized. Thisspecial angle of incidence is named after the Scottish physicist, Sir David Brewster (1781–1868).
Explanation
When light encounters a boundary between two media with different refractive indices, some of it is usually reflected as shown in the figure above. The fraction that is reflected is described by the Fresnel equations, and is dependent upon the incoming light's polarization and angle ofincidence.
The Fresnel equations predict that light with the p polarization (electric field polarized in the same plane as the incident ray and the surface normal) will not be reflected if the angle of incidence is
where n1 and n2 are the refractive indices of the two media. This equation is known as Brewster's law, and the angle defined by it is Brewster's angle.
The physical mechanism for thiscan be qualitatively understood from the manner in which electric dipoles in the media respond to p-polarized light. One can imagine that light incident on the surface is absorbed, and then reradiated by oscillating electric dipoles at the interface between the two media. The polarization of freely propagating light is always perpendicular to the direction in which the light is travelling. Thedipoles that produce the transmitted (refracted) light oscillate in the polarization direction of that light. These same oscillating dipoles also generate the reflected light. However, dipoles do not radiate any energy in the direction of the dipole moment. Consequently, if the direction of the refracted light is perpendicular to the direction in which the light is predicted to be specularly...
Cross polarization (sometimes written X-pol, in antenna slang) is the polarization orthogonal to the polarization being discussed. For instance, if the fields from an antenna are meant to be horizontally polarized, the cross-polarization in this case is vertical polarization. If the polarization is Right Hand Circularly Polarized (RHCP), the cross-polarization is Left HandCircularly Polarized (LHCP). See also Polarization.
This term arises because an antenna is never 100% polarized in a single mode (linear, circular, etc). Hence, two radiation patterns of an antenna are sometimes presented, the co-pol (or desired polarization component) radiation pattern and the cross-polarization radiation pattern.
The cross polarization may be specified for an antenna as apower level in negative dB, indicating how many decibels below the desired polarization's power level the x-pol power level is.
Polarización cruzada (a veces escrito X-Pol, en la jerga de antena) es la polarización ortogonal a la polarización que se discute. Por ejemplo, si los campos de una antena están destinados a ser polarizada horizontalmente, la polarización cruzada en este caso es lapolarización vertical. Si la polarización es la mano derecha de polarización circular (RHCP), la polarización cruzada es mano izquierda polarizada circularmente (LHCP). Véase también la polarización.
Este término se debe a que una antena no es 100% polarizada en un solo modo (lineal, circular, etc.) Por lo tanto, dos patrones de radiación de una antena se presentan a veces, la co-pol (o componentedeseado polarización) patrón de radiación y el patrón de radiación de polarización cruzada.
La polarización cruzada se puede especificar para una antena como un nivel de potencia en dB negativos, lo que indica cómo muchos decibelios por debajo del nivel de potencia de la polarización deseada es el nivel de potencia de x-pol.
Brewster's angle
An illustration of the polarization of light which isincident on an interface at Brewster's angle.
Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized. Thisspecial angle of incidence is named after the Scottish physicist, Sir David Brewster (1781–1868).
Explanation
When light encounters a boundary between two media with different refractive indices, some of it is usually reflected as shown in the figure above. The fraction that is reflected is described by the Fresnel equations, and is dependent upon the incoming light's polarization and angle ofincidence.
The Fresnel equations predict that light with the p polarization (electric field polarized in the same plane as the incident ray and the surface normal) will not be reflected if the angle of incidence is
where n1 and n2 are the refractive indices of the two media. This equation is known as Brewster's law, and the angle defined by it is Brewster's angle.
The physical mechanism for thiscan be qualitatively understood from the manner in which electric dipoles in the media respond to p-polarized light. One can imagine that light incident on the surface is absorbed, and then reradiated by oscillating electric dipoles at the interface between the two media. The polarization of freely propagating light is always perpendicular to the direction in which the light is travelling. Thedipoles that produce the transmitted (refracted) light oscillate in the polarization direction of that light. These same oscillating dipoles also generate the reflected light. However, dipoles do not radiate any energy in the direction of the dipole moment. Consequently, if the direction of the refracted light is perpendicular to the direction in which the light is predicted to be specularly...
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