Abstract

Among the devices that were used for microwave range applications, one that proved to be hard to miniaturize was resonator. Earlier wave guide-based cavity resonators were used for frequency selection and for material measurements. They used to give quality factors of a few thousand depending on the material used for making it, geometry, frequency and surface finish. For low power applications, planar microwave integrated circuits came. But the resonators in such planar circuits were giving quality factors mostly in double digits. This difficulty was overcoming with the advent of dielectric resonators (DR). They are ceramic pucks mostly in cylindrical geometry. They are made up of materials that give high dielectric constant (the wavelength of the electromagnetic field inside a material goes inversely as the square root of its dielectric constant) inside a abut with low dielectric loss and low temperature coefficient of resonant frequency (τf).