Hybrid resonant structure

A structure has a piezoelectric transducer (14) on a substrate (12) and comprising two conductive electrodes (16, 20) separated by a piezoelectric material layer (18), where the thickness (e18) of the layer is given by a specified relation. An additional layer (22) is placed on the surface of the electrode (20) opposite to the layer (18), where the thickness (e22) of the layer (22) is fixed for optimizing the acoustic-electric density inside the layer (18). Independent claims are also included for the following: (1) a frequency filter comprising a set of resonant structures; (2) a radio frequency transducer comprising an antenna associated to a resonant structure or to a frequency filter; and (3) the production of a hybrid bulk acoustic wave resonant structure.