Dielectric resonator

Dielectric resonators are key elements for filters, low phase noise oscillators and frequency standards in current microwave communication technology. Applications of dielectric resonators in filter design have become more and more popular due to impressive advantages, such as small size, low weight, low loss (high Q), and common commercial availability. Dielectric resonators are used in microwave circuits for concentrating electric fields. They can be used to form filters, oscillators, triplexers and other circuits. The higher the dielectric constant of the dielectric material out of which the resonator is formed, the smaller the space within which the electric fields are concentrated. Dielectric resonators possess resonator quality factors (Q) comparable to cavity resonators, strong linearity at high power levels, weak temperature coefficients, high mechanical stability and small size. Microwave oscillators are used in transmission systems and more particularly close to the antenna in order to carry out a frequency transposition between an intermediate frequency band and a transmission frequency band. Dielectric resonator oscillators are commonly used in high-precision RF and microwave systems to generate high-frequency signals of extremely good spectral purity. A typical dielectric resonator for use in the microwave band is formed using a rectangular or cylindrical dielectric block having a coaxial through-hole wherein an inner conductor is formed on the inner surface of the through-hole and an outer conductor is formed on the outer surface of the dielectric block.