Temperature and Frequency Dependence of Complex Permittivity in Metal Oxide Dielectrics: Theory, Modelling and Measurement : Springer : 9783319830766 : 3319830767 : 22 Apr 2018 : This thesis investigates the dielectric properties of metal-oxide ceramics at microwave frequencies. It also demonstrates for the first time that a theory of harmonic phonon coupling can effectively predict the complex permittivity of metal oxides as a function of temperature and frequency. Dielectric ceramics are an important class of materials for radio-frequency, microwave and emergent terahertz technologies. Their key property is complex permittivity, the real part of which permits the miniaturisation of devices and the imaginary part of which is responsible for the absorption of electromagnetic energy. Absorption limits the practical performance of many microwave devices such as filters, oscillators, passive circuits and antennas. Complex permittivity as a function of temperature for low-loss dielectrics