Lf. Chen et al., Amendment of cavity perturbation method for permittivity measurement of extremely low-loss dielectrics, IEEE INSTR, 48(6), 1999, pp. 1031-1037
Citations number
27
Categorie Soggetti
Instrumentation & Measurement
Journal title
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
The quality factor of a resonant cavity may increase after introducing an e
xtremely low-loss dielectric, so the conventional cavity perturbation metho
d, widely used in dielectric permittivity measurement, may be invalid for e
xtremely low-loss dielectric samples. After a brief review of the conventio
nal cavity perturbation theory, this paper discusses the change of quality
factor of a resonant cavity due to the introduction of a dielectric sample,
A new concept, expected quality factor Q(0), is introduced in this paper t
o denote the quality factor of a resonant cavity loaded,vith a strictly no-
loss sample, and a calibration procedure is proposed to find the frequency
dependence of Q(0) The conventional resonant perturbation formulas are then
amended by substituting the quality factor before the perturbation with th
e expected quality factor Q(0) corresponding to the frequency after the per
turbation, Experiments show that the accuracy of resonant perturbation meth
od has been greatly increased after the amendment, especially for extremely
low-loss dielectric samples.