Dielectric resonators raise your high-Q

High-quality resonating elements are the key to the function of most microwave circuits and systems. They are fundamental to the operation of filters and oscillators, and the performance of these circuits is primarily limited by the resonator quality factor. At microwave frequencies, the quality factor (Q) of metal transmission line resonant circuits is proportional to volume. As a result, waveguide structures are often employed to increase Q at the expense of size, weight, and cost. Dielectric resonators overcome these limitations due to the fact that their losses are dominated by dielectric loss (loss tangent), and only in small part to metallic losses (housing). Dielectric losses are improving constantly, whereas metal losses, with the exception of superconductors, have remained substantially the same. These resonators can be made to perform the same functions as waveguide filters, but are, in contrast, very small, stable and lightweight. The popularization of low-loss dielectric resonators roughly coincides with the miniaturization of many of the other associated elements of most microwave circuits. When taken together, these technologies permit the realization of small, reliable, lightweight and stable microwave systems.