Tunable ferroelectric resonator arrangement

A tunable resonator apparatus comprising:

• a first resonator;
• a second resonator;
• said first resonator being non-tunable;
• said second resonator being a tunable ferroelectric resonator;
• wherein the first resonator and the second resonator work as a single resonator;
• a ground plane for separating said first and second resonators, the ground plane being common for said first and second resonators;
• coupling means for providing coupling between said first resonator and said second resonator;
• and
• wherein for tuning of the resonator apparatus, a biasing voltage is applied to the second resonator.

A method of tuning a resonator apparatus, comprising:

• providing a first, non-tunable, resonator,
• providing a second tunable resonator,
• separating the first and second resonators by a common ground plane,
• providing coupling means in said common ground plane such that the first and second resonators becomes a coupled resonator apparatus, thereby allowing transfer of electromagnetic energy between the first and second resonators,
• applying a biasing/tuning voltage to said second resonator for changing the resonating frequency, and the loss tangent of the second resonator, and the transfer of electromagnetic energy to the first resonator,
• optimizing application of the biasing voltage such that influence of the increased loss tangent in the first resonator, on the coupled resonator apparatus, will be compensated for, by an increased transfer of electromagnetic energy to the first resonator.