A Novel Sensor With Two Dielectric Coupled Resonators for Permittivity and Permeability Synchronous Characterization

The accurate measurement of permittivity and permeability facilitates the development and application of new materials. This study proposed a dielectric sensor with two coupled dielectric resonators. The proposed sensor could simultaneously characterize the permittivity and permeability of materials by constructing two resonant modes. The sensitivity of the permeability and permittivity characteristic modes was 0.283 and 0.055 GHz/IU, respectively. Compared to a single dielectric sensor, the coupled structure improved the sensitivity of the sensor. In experiments, F4B, FR4, pure PDMS, PDMS-Fe3O4 (30%), and PDMS-Fe3O4 (50%) plates were employed as materials for testing. The simulation and experimental results demonstrated that the permittivity sensing was dependent on a strong electric field acting vertically on the surface of the material, and the permeability sensing was dependent on a strong magnetic field acting vertically on the surface of the material. Thus, a general mechanism was formulated, and a method to design resonant sensors that capable of simultaneously characterizing the permittivity and permeability of single sample at one test location was developed.