Piezoelectric transducer-controlled tunable hairpin bandpass filter

A piezoelectric transducer (PET)-controlled tunable hairpin bandpass filter (BPF) is introduced. A dielectric perturber is attached to a PET cantilever beam and suspended above the hairpin BPF. The PET actuator vertically lifts up or pulls down the attached dielectric perturber using a DC bias voltage. The dielectric perturber changes the effective permittivity, causing a variation in the BPF´s effective capacitance. This changes the centre frequency and passband of the BPF. The hairpin BPF is designed at 5.8 GHz with a fractional bandwidth (FBW) of 0.414%. The fabricated BPF shows a measured insertion loss of less than 2.5 dB and a return loss of greater than 12 dB in the frequency tuning range.