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An accurate and simple technique for evaluation of high permittivity materials, (Bs,Sr) TiO3 (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 (εr) and tanδ are evaluated by numerical calculations using the extended spectral domain approach taking the conductor thickness effect into consideration. The estimated εr's of Ba0.7Sr0.3TiO3, Ba0.5Sr0.5TiO3, and Ba0.3Sr0.7TiO3 are 660, 1650, and 4450, respectively. The εr decreases slightly as frequency increased due to dielectric dispersion. This technique enables the evaluation of even a small deviation in high permittivity materials.
Microwave Conference Proceedings, 2005. APMC 2005. Asia-Pacific Conference Proceedings (Volume:4 )
Date of Conference: 4-7 Dec. 2005