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(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 (epsilon(r)) and tan delta are evaluated by numerical calculations using the extended spectral domain approach taking the conductor thickness effect into consideration. The estimated epsilon(r)'s of Ba(0.7)Sr(0.3)TiO(3), Ba(0.5)Sr(0.5)TiO(3), and Ba(0.3)Sr(0.7)TiO(3) are 660, 1650, and 4450, respectively. The epsilon(r) decreases slightly as frequency increased due to dielectric dispersion. This technique enables the evaluation of even a small deviation in high permittivity materials.