Probe‐Loaded Coaxial Cavity With High Quality Factor for Complex Permittivity Measurement

ABSTRACT This paper presents the probe‐loaded coaxial resonant cavity. The probe is non‐contact, embedded within the inner conductor of the re‐entry coaxial cavity. The probe emits a portion of the resonant cavity's energy, which is then applied to the material under measurement. This process enables the assessment of complex permittivity in thin‐film materials. Through simulation analysis of key parameters such as probe embedding depth, length, and gap, it was discovered that the probe embedding depth exhibits considerable tolerance toward the requirements for high‐quality‐factor design. It has been demonstrated that designers do not necessarily require precise control over the probe embedding depth to achieve a relatively high quality factor. This approach has been demonstrated to be highly advantageous for both the design and practical assembly of resonant cavities. The complex permittivity of the substrate was measured using the resonant cavity perturbation method, with the resultant data indicating a quality factor greater than 1800 at the TEM 001 mode. It has been demonstrated through experimental measurements that the proposed cavity is capable of producing reliable results when it comes to substrate measurement.