Resonant State
Electromagnetic energy distribution within a dielectric resonator creates a specific transverse electric field pattern characterized by high rotational symmetry and minimal radiation losses. This distribution is known as the TE01delta mode, which represents the primary resonant state used for characterizing low-loss substrate materials. It features a circular electric field that is completely parallel to the plane of the laminate sample under test.
This field orientation is highly sensitive to the in-plane dielectric properties of the substrate. Because the electric field does not cross the boundary of the sample vertically, it minimizes the effect of any air gaps between the sample and the metal cavity walls.
Cavity Measurement
Measuring the resonant frequency of this mode provides a highly accurate way to calculate the substrate relative permittivity. The quality factor of the mode is used to determine the dissipation factor of the laminate material. Since this mode has low radiation loss, it allows the extraction of very small loss tangents, even down to decimal fractions.
This measurement requires a vector network analyzer.
Substrate Evaluation
High-frequency material manufacturers use this resonant mode to qualify new low-loss laminate formulations during research and development. It provides a standardized method to compare different resin systems at high frequencies. The test results help guarantee that the material will perform as expected in demanding radar and communication assemblies.
This prevents field failures after deployment.
