cavity resonator

(electromagnetism) A space totally enclosed by a metallic conductor and excited in such a way that it becomes a source of electromagnetic oscillations. Also known as cavity; microwave cavity; microwave resonance cavity; resonant cavity; resonant chamber; resonant element; rhumbatron; tuned cavity; waveguide resonator.

An enclosure capable of resounding or resonating and thereby intensifying sound tones or electromagnetic waves. Resonance is the phenomenon which results when the frequency of the impressed driving force is the same as the natural vibration of the cavity. Vibrating rods, the tuning fork, musical instrument strings, radio and television channel tuners, and so forth, constitute resonating systems as well. The cavity resonator enclosure has a volume which stores energy oscillating between one form and another. In the case of sound, the oscillation is between displacement and velocity of particles. In the case of electromagnetic waves, the energy oscillates between the magnetic and the electric fields. See also Musical instruments; Tuning fork; Vibration.

Cavity pipes are used as resonators in musical instruments such as pipe organs and flutes to increase their sonority. The frequency of resonance is determined (to a degree of approximation) by the length of the pipe, by the velocity of sound at the ambient temperature and pressure, by the intensity of the driving force, and by the condition at the ends of the pipe: closed or open. The resulting frequency is related to multiples of quarter-wavelengths or half-wavelengths (depending on the end conditions) contained in the length of pipe. The driving force, if sufficiently strong, can force oscillations to occur at overtone frequencies which are higher multiples of the lowest or fundamental frequency, as well as at the fundamental. See also Acoustic resonator; Sound.

At very high radio frequencies, losses due to radiation can be eliminated and resistive losses can be minimized by using closed resonant cavities instead of lumped-circuit resonators. A cavity resonator stores both magnetic and electric fields, the energy oscillating between the two, losing energy only to the conducting walls if a perfect dielectric fills the space. The resonant frequency of the cavity is determined by the shape of the cavity and the mode, or allowable field distribution, of the electromagnetic energy that the cavity contains. Microwave transmission devices use such cavities. See also Klystron; Magnetron.

The noun has one meaning:

Meaning #1: a hollow chamber whose dimensions allow the resonant oscillation of electromagnetic or acoustic waves
  Synonyms: resonator, resonating chamber