Four-Pole Tunable Band-Pass Filters Based on Two Dual Mode SrTiO3 Disc Resonators

A four-pole tuneable band-pass filter based on two STO disc resonators (0.5mm thick, 7.0 mm in diameter) is designed and characterized experimentally. The filter with a center frequency about 0.5 GHz and bandwidth less than 2.0 % is utilised on two degenerate TM110 modes of parallel-plate resonators to operate at temperature 60K. The change in center frequency under DC bias 500V is about 8%.