摘要：Dielectric resonators are key components in many microwave and millimetre wave circuits and applications, including.hig.-Q filters and frequency-determining.elements for precision frequency synthesis. Multilayered and bulk low-loss sing.e crystal and polycrystalline dielectric structures have become very important for desig.ing.these devices. Proper desig. requires careful electromag.etic characterisation of low-loss material properties. This includes exact simulation with precision numerical software and precise measurements of resonant modes. For example, we have developed the Whispering.g.llery mode technique, which has now become the standard for characterizing.low-loss structures. This paper will review some of the common characterisation techniques used in the microwave to millimetre wave frequency reg.me.