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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.
An electromagnetic '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.

Contents

Electromagnetic

Cavity resonators

Examples

Patents

Acoustic resonators

Automobiles

Musical instruments

Percussion instruments

Stringed instruments

See also

External links

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.

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.

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 magnetron tube in a microwave oven (see also klystron).
The cavity magnetron is a vacuum tube with a filament in the center of an evacuated, lobed, circular chamber. A perpendicular magnetic field is imposed by a permanent magnet. The magnetic field causes the electrons, attracted to the (relatively) positive outer part of the chamber, to spiral outward in a circular path rather than moving directly to this anode. Spaced about the rim of the chamber are cylindrical cavities. The cavities are open along their length and so connect the common cavity space.As electrons sweep past these openings they induce a resonant high frequency radio field in the cavity, which in turn causes the electrons to bunch into groups. A portion of this field is extracted with a short antenna that is connected to a waveguide (a metal tube usually of rectangular cross section). The waveguide directs the extracted RF energy to the load, which may be a cooking chamber in a microwave oven or a high gain antenna in the case of radar.
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.

Patents

The USPTO classifies devices and systems where the resonator device is an or 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


★ : ''Electromagnetic resonator''—W. Dallenbach

★ : ''Inductance-capacitance resonance circuit''—H. B. Rex

★ : ''Cavity resonator circuit''—P. S. Carter

★ : ''Ultra short wave radio system''—S. A. Schelkunoff

★ : ''Cavity resonator circuit''—P. S. Carter

★ : ''High frequency resonator and circuit therefor''—P. S. Carter

★ : ''Cavity resonator''—H. Bushholz

★ : ''High frequency tanks and resonant cavities''—S. A. Schelkunoff

★ : ''Frequency stabilization at ultra high frequencies''—F. B. Llewellyn

★ : ''Resonant system for ultra short waves''—Willi Engbert

★ : ''Transmission of guided waves''—G. C. Southworth

★ : ''Transmitter and receiver for electromagnertic waves''—R. Weyrich

★ : ''Electrical circuit arrangement''—R. K. Potter

★ : ''Electrical circuit arrangement''—R. K. Potter

★ : ''Electrical circuit arrangement''—R. K. Potter

;Reissued


★ : ''High-power high-frequency electron discharge apparatus''—R. H. Varian

★ : ''High efficiency resonate circuit''—W. W. Hansen

★ : ''Modulation system''—W. W. Hansen

Acoustic resonators

The most familiar audio resonator is perhaps the Helmholtz resonator although many other structures can exhibit audio resonances.

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.

Musical instruments

Most musical instruments include resonators to enhance the sound of the instrument.

Percussion instruments

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.
The tremolo effect of a vibraphone is obtained by a mechanism which opens and shuts the resonators.

Stringed instruments

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. Another example is the Moonlander, a string resonator guitar with 12 sympathetic strings.

See also

★ Resonance

★ Mechanical resonance

★ Electrical resonance

★ Acoustic resonance

External links

★ "Acoustics of Resonators" by Leigh Howard Stevens