Bandpass filter for a radio-frequency signal and tuning method therefor

A bandpass filter for a radio-frequency signal comprises an input section for a signal to be filtered, an output section for the filtered signal and at least one resonator electromagnetically or directly coupled to input and output sections. The shape of the resonator has binary rotation symmetry and/or mirror symmetry with respect to a signal propagation direction and is adapted to be excited into an oscillation having the same type of symmetry by applying the signal to be filtered to the input section.