An accurate measurement method of high permittivity materials by numerical analysis of coplanar waveguide

An accurate and simple technique for evaluation of high permittivity materials, (Bs,Sr) TiO/sub 3/ (BST) ceramics, in the microwave region is developed with assistance of full-wave analysis of a coplanar waveguide (CPW). S-parameters of the CPW are measured from 0.5 to 40 GHz, and effective permittivity and attenuation constants at each frequency are obtained from the S-parameter data. Relative permittivity (/spl epsiv//sub r/) and tan/spl delta/ are evaluated by numerical calculations using the extended spectral domain approach taking the conductor thickness effect into consideration. The estimated /spl epsiv//sub r/'s of Ba/sub 0.7/Sr/sub 0.3/TiO/sub 3/, Ba/sub 0.5/Sr/sub 0.5/TiO/sub 3/, and Ba/sub 0.3/Sr/sub 0.7/TiO/sub 3/ are 660, 1650, and 4450, respectively. The /spl epsiv//sub r/ decreases slightly as frequency increased due to dielectric dispersion. This technique enables the evaluation of even a small deviation in high permittivity materials.