Dielectric resonator

A dielectric resonator (also dielectric resonator osciallator, DRO) is an electronic component that exhibits resonance for a narrow range of frequencies, generally in the microwave band. The resonance is similar to that of a circular hollow metallic waveguide, except that the boundary is defined by large change in permittivity rather than by a conductor. Dielectric resonators generally consist of a "puck" of ceramic that has a large dielectric constant and a low dissipation factor. The resonance frequency is determined by the overall physical dimensions of the puck and the dielectric constant of the material.

Dielectric resonators are often used to provide a frequency reference in an oscillator circuit.

A dielectric resonator is generally enclosed in an RF shield to prevent it radiating. An unshielded dielectric resonator can be used as an antenna. This type of antenna is usually called a DRA (Dielectric Resonator Antenna).