Amendment of Cavity Perturbation Technique for Loss Tangent Measurement at Microwave Frequencies

Theoretically, the quality factor of a metal resonant cavity will be increased after introducing a lossless dielectric sample. However, for the conventional cavity perturbation method, widely used on the measurements of microwave dielectric properties, this increment of quality factor is not put into the consideration of calculation on loss tangent measurement. Therefore, the conventional resonant perturbation formulae for dielectric loss measurement should be amended. This amendment is introduced in this study and the measuring error on loss tangent on the conventional formula is discussed. Experiments have shown the improvement of measurement accuracy by this modification.