PERMITTIVITY MEASUREMENT OF THIN DIELECTRIC MATERIALS FROM REFLECTION-ONLY MEASUREMENTS USING ONE-PORT VECTOR NETWORK ANALYZERS

Abstract

We have proposed a simple waveguide method for complex permittivity determination of dielectric materials which are not completely fllling the entire sample holder. The method reconstructs the permittivity from measured re∞ection-only scattering parameters by a one-port vector network analyzer of two conflgurations of the sample holder. It not only eliminates the necessity of any knowledge of the location of the shifted sample inside its holder but also decreases measurement errors occurring with the presence of undesired air gaps, which seriously afiect the measurement accuracy of transmission- only measurements, present between the sample and holder walls. Furthermore, the reconstruction of permittivity can be realized by any one-port vector network analyzer, which is less expensive than their two-port counterparts. Therefore, the proposed method is cost-efiective. We have analyzed the accuracy of the proposed method and noted a good compromise between the reference data and measured values of permittivities of low-loss polyvinyl-chloride and polytetra∞uoro.ethylene samples (less than 8 percent for dielectric constant and less than 15 percent for loss tangent values).