8. Conclusion

Dielectric resonators are the focus of research into material compositions and processes, as well as shaping to meet new microwave filter models. At high frequencies above 10 GHz, materials that inherently have higher losses are being improved to target Q x f products in excess of 200 THz. At lower frequencies, for filtering solutions (e.g. radiotelephone base stations), demands on resonator quality factor or dielectric losses are more varied, depending on the resonance mode or power level of the application. In TEM mode, Q factors are of the order of 1,000 for low powers and maximum miniaturization. In TE mode, Q factors range from 10,000 to over 20,000, depending on power. In TM mode, the case is intermediate between the other two modes. Finally, oscillator applications (satellite TV reception, alarms, etc.) require flexibility in temperature coefficient, from 0 to over 15 ppm/°C, to...