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Link to original content: http://dbpedia.org/resource/Microwave_cavity
About: Microwave cavity
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A microwave cavity or radio frequency (RF) cavity is a special type of resonator, consisting of a closed (or largely closed) metal structure that confines electromagnetic fields in the microwave region of the spectrum. The structure is either hollow or filled with dielectric material. The microwaves bounce back and forth between the walls of the cavity. At the cavity's resonant frequencies they reinforce to form standing waves in the cavity. Therefore, the cavity functions similarly to an organ pipe or sound box in a musical instrument, oscillating preferentially at a series of frequencies, its resonant frequencies. Thus it can act as a bandpass filter, allowing microwaves of a particular frequency to pass while blocking microwaves at nearby frequencies.

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  • Consideremos una guía de ondas que terminamos en cortocircuito. Si a una distancia de media longitud de onda (en la guía) colocamos otro, la cavidad así formada permite la existencia de una onda estacionaria, de aquellas frecuencias cuyas semilongitudes de onda sean múltiplos enteros de la longitud de la guía. En otras palabras: la estructura resuena a esas frecuencias, por lo que se llama cavidad resonante. En realidad, esta estructura totalmente cerrada no tiene aplicación práctica y, además, tampoco contiene una onda estacionaria ya que no hay ningún generador. Pero, si acoplamos la estructura a un generador, por ejemplo, a través de un orificio o un bucle de hilo conductor, situados convenientemente, se podrán excitar estas ondas estacionarias. El análisis de la estructura conduce al cálculo de los modos que permite, TEXYZ y TMXYZ. El acoplo se realizará para excitar el modo de interés. Los modos tienen tres subíndices debido a que la onda estacionaria se puede propagar en las tres direcciones del espacio. La existencia de modos superiores indica que la cavidad resonará a la frecuencia fundamental y a sus armónicos. Como la energía almacenada en la cavidad resonante depende de su volumen y las pérdidas, de su superficie, con cavidades resonantes cilíndricas se puede obtener valores de Q muy elevados. Aunque esta descripción se ha realizado pensando en ondas electromagnéticas, es igualmente válida para otros tipos de ondas. Los tubos de un órgano, por ejemplo, son cavidades resonantes sintonizados -afinados- a la nota correspondiente que filtran el ruido producido por el aire al rozar la lengüeta, al excitar solamente la frecuencia de resonancia del tubo. (es)
  • A microwave cavity or radio frequency (RF) cavity is a special type of resonator, consisting of a closed (or largely closed) metal structure that confines electromagnetic fields in the microwave region of the spectrum. The structure is either hollow or filled with dielectric material. The microwaves bounce back and forth between the walls of the cavity. At the cavity's resonant frequencies they reinforce to form standing waves in the cavity. Therefore, the cavity functions similarly to an organ pipe or sound box in a musical instrument, oscillating preferentially at a series of frequencies, its resonant frequencies. Thus it can act as a bandpass filter, allowing microwaves of a particular frequency to pass while blocking microwaves at nearby frequencies. A microwave cavity acts similarly to a resonant circuit with extremely low loss at its frequency of operation, resulting in quality factors (Q factors) up to the order of 106, compared to 102 for circuits made with separate inductors and capacitors at the same frequency. They are used in place of resonant circuits at microwave frequencies, since at these frequencies discrete resonant circuits cannot be built because the values of inductance and capacitance needed are too low. They are used in oscillators and transmitters to create microwave signals, and as filters to separate a signal at a given frequency from other signals, in equipment such as radar equipment, microwave relay stations, satellite communications, and microwave ovens. RF cavities can also manipulate charged particles passing through them by application of acceleration voltage and are thus used in particle accelerators and microwave vacuum tubes such as klystrons and magnetrons. (en)
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  • 22748103 (xsd:integer)
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  • 14112 (xsd:nonNegativeInteger)
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  • 1084881071 (xsd:integer)
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dbp:date
  • October 2012 (en)
dbp:reason
  • What is l? What is k? What is eta? What is R_s? Why isn't this symmetric under the interchange of the three dimensions or mode labels? This formula is not even dimensionless, and Q should be a dimensionless number! (en)
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rdfs:comment
  • Consideremos una guía de ondas que terminamos en cortocircuito. Si a una distancia de media longitud de onda (en la guía) colocamos otro, la cavidad así formada permite la existencia de una onda estacionaria, de aquellas frecuencias cuyas semilongitudes de onda sean múltiplos enteros de la longitud de la guía. En otras palabras: la estructura resuena a esas frecuencias, por lo que se llama cavidad resonante. Como la energía almacenada en la cavidad resonante depende de su volumen y las pérdidas, de su superficie, con cavidades resonantes cilíndricas se puede obtener valores de Q muy elevados. (es)
  • A microwave cavity or radio frequency (RF) cavity is a special type of resonator, consisting of a closed (or largely closed) metal structure that confines electromagnetic fields in the microwave region of the spectrum. The structure is either hollow or filled with dielectric material. The microwaves bounce back and forth between the walls of the cavity. At the cavity's resonant frequencies they reinforce to form standing waves in the cavity. Therefore, the cavity functions similarly to an organ pipe or sound box in a musical instrument, oscillating preferentially at a series of frequencies, its resonant frequencies. Thus it can act as a bandpass filter, allowing microwaves of a particular frequency to pass while blocking microwaves at nearby frequencies. (en)
rdfs:label
  • Cavidad resonante (es)
  • Microwave cavity (en)
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