Microwave properties of (Ba,Sr)TiO3 ceramic films and phase-shifters on their base

The small signal dielectric properties (epsilon, tan delta) of ceramic (Ba,Sr)TiO3 (BSTO) films in the frequency range (1-30) GHz we're under investigation. The Q-factor and tunability were measured for planar BSTO ceramic varactors and are presented in comparison with similar parameters for semiconductor varactors. To illustrate the possibility of the use of BSTO ceramic films at 30 GHz, a phase shifter based on grounded coplanar waveguide (CWG) has been designed and experimentally tested. The device demonstrated phase shift up to Delta phi = 370 degrees under the bias voltage (0-350) V and insertion loss L = (4-6) dB in all range of bias voltages.