Editing Resonator (section)

{{short description|Device or system that exhibits resonance}}
{{Other uses}}
{{refimprove|date=January 2008}}

A '''resonator''' is a device or system that exhibits [[resonance]] or resonant behavior. That is, it naturally [[Oscillation|oscillates]] with greater [[amplitude]] at some [[frequency|frequencies]], called [[Resonance frequency|resonant frequencies]], than at other frequencies.  The oscillations in a resonator can be either [[Electromagnetic radiation|electromagnetic]] or mechanical (including [[Acoustics|acoustic]]). Resonators are used to either generate waves of specific frequencies or to select specific frequencies from a signal.  Musical instruments use [[Musical acoustics|acoustic]] resonators that produce sound waves of specific tones. Another example is [[crystal oscillator|quartz crystals]] used in electronic devices such as [[radio transmitter]]s and [[quartz clock|quartz watches]] to produce oscillations of very precise frequency.

[[File:Two dim standing wave.gif|right|thumb|upright=0.6|A standing wave in a rectangular cavity resonator]]
A '''cavity resonator''' is one in which waves exist in a hollow space inside the device.  In electronics and radio, [[Microwave cavity|microwave cavities]] consisting of hollow metal boxes are used in microwave transmitters, receivers and test equipment to control frequency, in place of the [[tuned circuit]]s which are used at lower frequencies.  Acoustic cavity resonators, in which sound is produced by air vibrating in a cavity with one opening, are known as [[Helmholtz resonance|Helmholtz resonators]].