14 GHz Tunable Filters Base on Ferroelectric Films

Two new types of microwave four-pole tunable waveguide filters containing planar (Ba,Sr)TiO3 film ferroelectric capacitors are presented. The frequency tuning of the filters is due to the variation of ferroelectric capacitance with applied dc voltage. The parameters of the Ku-band filters are the following: 1 dB bandwidth is ∼0.9%, the range of tuning is 350 MHz and 260 MHz, insertion losses are not more than 4.7 dB and 3 dB respectively.