8. Conclusion

Dielectric resonators are the focus of research into material compositions and processes, as well as into shaping techniques designed to meet the requirements of new microwave filter designs. At high frequencies, above 10 GHz, materials that inherently have higher losses are being improved to achieve products with a quality factor that increases with frequency, $Q\times f$ , exceeding 200 THz. At lower frequencies, for filtering applications (such as radiotelephone base stations), the requirements for resonator quality factor or dielectric loss vary depending on the resonance mode or the power level of the application. In TEM mode, the factors $Q$...