Resonator
From Wikipedia, the free encyclopedia
A resonator is a device or system that exhibits resonance or resonant behavior. Many objects that use resonant effects are referred to simply as resonators. Examples of resonators are discussed in this article. A cavity resonator is a resonator composed of a space that is usually surrounded by a dielectric that uses resonance to select a specific band of frequencies.
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[edit] Electromagnetic
A distributed parameter resonator of the distributed network type has capacitance, inductance, and resistance which cannot be isolated into separate lumped capacitors, inductors, or resistors. The time factor of propagation of wave energy in the network is appreciable. Resonators can be of the dielectric type or magnetic type. A hollow conductor that uses resonance to amplify an electromagnetic wave is called a cavity resonator. In the context of electronic components, resonator may refer to a ceramic resonator, a device used to produce an oscillation of a specific frequency, primarily for use as the clock signal for digital circuits. A single layer coil (or solenoid) that is used as a secondary or tertiary winding in a Tesla Coil or Magnifying Transmitter is also called a resonator.
[edit] Cavity resonators
The cavity has interior surfaces which reflect a wave of a specific frequency. When a wave that is resonant with the cavity enters, it bounces back and forth within the cavity, with low loss (See standing wave). As more wave energy enters the cavity, it combines with and reinforces the standing wave, increasing its intensity.
[edit] Examples
Some examples of cavity resonators include the tube of a flute, the body of a violin (this being an example of a Helmholtz resonator), and the klystron tube in a microwave oven (see also magnetron).
The klystron tube waveguide is a beam tube including at least two apertured cavity resonators. The beam of charged particles passes through the apertures of the resonators in succession. A collector electrode is provided to intercept the beam after passing through the resonators. The first resonator causes bunching of the particles passing through it. The bunched particles travel in a field-free region where further bunching occurs, then the bunched particles enter the second resonator giving up their energy to excite it into oscillations. It is a particle accelerator that works in conjunction with a specifically tuned cavity by the configuration of the structures. On the beamline of an accelerator system, there are specific sections that are cavity resonators for RF.
The reflex klystron is a klystron utilizing only a single apertured cavity resonator through which the beam of charged particles passes, first in one direction. A repeller electrode is provided to repel (or redirect) the beam after passage through the resonator back through the resonator in the other direction and in proper phase to reinforce the oscillations set up in the resonator.
In a laser, light is amplified in a cavity resonator which is usually composed of two or more mirrors. Thus an optical cavity, also known as a resonator, is a cavity with walls which reflect electromagnetic waves (light). This will allow standing wave modes to exist with little loss outside the cavity.
[edit] Patents
The USPTO classifies devices and systems where the resonator device is an enclosure or cavity so constructed that the field configuration excited within the boundaries of the device includes longitudinal as well as transverse field components as Class 333, Wave transmission lines and networks, and Subclass 227.
- Numbered
- U.S. Patent 2199045: Electromagnetic resonator—W. Dallenbach
- U.S. Patent 2611094: Inductance-capacitance resonance circuit—H. B. Rex
- U.S. Patent 2444152: Cavity resonator circuit—P. S. Carter
- U.S. Patent 2372228: Ultra short wave radio system—S. A. Schelkunoff
- U.S. Patent 2357314: Cavity resonator circuit—P. S. Carter
- U.S. Patent 2357313: High frequency resonator and circuit therefor—P. S. Carter
- U.S. Patent 2315313: Cavity resonator—H. Bushholz
- U.S. Patent 2235506: High frequency tanks and resonant cavities—S. A. Schelkunoff
- U.S. Patent 2262020: Frequency stabilization at ultra high frequencies—F. B. Llewellyn
- U.S. Patent 2250096: Resonant system for ultra short waves—Willi Engbert
- U.S. Patent 2106769: Transmission of guided waves—G. C. Southworth
- U.S. Patent 2044413: Transmitter and receiver for electromagnertic waves—R. Weyrich
- U.S. Patent 2030180: Electrical circuit arrangement—R. K. Potter
- U.S. Patent 2030179: Electrical circuit arrangement—R. K. Potter
- U.S. Patent 2030178: Electrical circuit arrangement—R. K. Potter
- Reissued
- U.S. Patent RE23534: High-power high-frequency electron discharge apparatus—R. H. Varian
- U.S. Patent RE23019: High efficiency resonate circuit—W. W. Hansen
- U.S. Patent RE22990: Modulation system—W. W. Hansen
[edit] Automobiles
A resonator is one part in exhaust systems that works with the muffler to reduce noise, by making sound waves "cancel each other out"[1]. The "exhaust note" is an important feature for many vehicle owners, so both the original manufacturers and the after-market suppliers use the resonator to enhance the sound
[edit] Musical instruments
Most musical instruments include resonators to enhance the sound of the instrument. In many keyboard percussion instruments, below the centre of each note is a tube, which is an acoustic cavity resonator, referred to simply as the resonator. The length of the tube varies according to the pitch of the note, with higher notes having shorter resonators. The tube is open at the top end and closed at the bottom end, creating a column of air which resonates when the note is struck. This adds depth and volume to the note. In string instruments, the body of the instrument is a resonator.
In Camille Saint-Saëns' Danse Macabre, a skeleton's dance is depicted by a xylophone. Since the instrument in Saint-Saëns' day did not have resonators, it is often performed with resonators removed (or covered). This makes sound of the instrument more brittle and bone-like. The tremolo effect of a vibraphone is obtained by a mechanism which opens and shuts the resonators. String instruments such as the bluegrass banjo may also have resonators. Many five-string banjos have removable resonators, to allow the instrument to be used with resonator in bluegrass style, or without in folk music style. The term resonator, used by itself, may also refer to the resonator guitar.
