Evaluation of the relative permittivity of BaxSr1-xTiO3 ceramics at microwave frequencies using microstrip ring resonators

The microstrip-ring-resonance technique has been applied to determine the dielectric properties of high-permittivity barium strontium titanate (BaxSr1-xTiO3) ceramics at microwave frequencies. A microstrip ring resonator of diameter 5 mm has been fabricated on the ceramics by the standard photolithography process. The transmission coefficient S21 spectra for the resonators have been measured using a vector network analyzer and simulated using a commercial electromagnetic simulation package, IE3D. By fitting the observed spectra to the simulated spectra, e and tan δ of the BaxSr1-xTiO3 ceramics have been determined. The results obtained by this technique are in agreement with those determined by other conventional methods. This technique is relatively simple, especially for high-permittivity materials, since there are less rigorous requirements on the sample and the test conditions.