| Summary: | 碩士 === 國立清華大學 === 物理學系 === 105 === Characterizing the electromagnetic properties helps us to understand the microwave-material interaction and to provide the foundation in engineering studies. For the precise measurement, the commonly used technique, cavity perturbation, suffers from the interplay between electric and magnetic fields. However, our proposed method, the dual-cavity system, can almost separate the influence of each field on the sample to characterize the relative complex permittivity and permeability, respectively. We prepared samples including three homemade epoxy-based composites (Fe3O4, silver, and carbonyl iron) and a commercial ferrite garnet. The complex permittivity and permeability of each composite can be determined and be well analyzed with the effective medium theories. With external magnetic fields, the electromagnetic properties of each composite change differently due to their own magnetism. For the ferrite garnet, distinct transverse electromagnetic (TEM) modes are enhanced with different magnetic bias fields.
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