Electroacoustic transducer having reduced losses due to transverse emission and improved performance due to suppression of transverse modes

An electroacoustic transducer, comprising:

• a piezoelectric substrate;
• two busbars arranged on the substrate;
• two electrodes arranged on the substrate, each electrode having interdigital electrode fingers interconnected with a respective one of the two busbars, the electrodes configured for excitation of an acoustic wave;
• a dielectric layer covering at least the busbars;
• and
• a plurality of regions running parallel to an acoustic track, wherein the acoustic wave experiences different longitudinal propagation velocity in each of the regions, the plurality of regions comprising:
• a central excitation region with a first longitudinal velocity;
• inner edge regions flanking the central excitation region on both sides, wherein a second longitudinal velocity in the inner edge regions is higher than the first longitudinal velocity of the central excitation region;
• outer edge regions flanking the inner edge regions, wherein third longitudinal velocity in the outer edge regions is higher than one of the first longitudinal velocity in the central excitation region or the second longitudinal velocity in the inner edge regions;
• regions of the busbars flanking the outer edge regions, wherein a fourth longitudinal velocity in the regions of the busbars is lower than the third longitudinal velocity in the outer edge regions.

An electroacoustic transducer, comprising:

• a piezoelectric substrate;
• two busbars arranged on the substrate;
• two electrodes arranged on the substrate, each electrode having interdigital electrode fingers interconnected with a respective one of the two busbars, the electrodes configured for excitation of an acoustic wave;
• a dielectric layer covering at least the electrode fingers of at least one of the electrodes;
• and
• a plurality of regions running parallel to an acoustic track, wherein the acoustic wave experiences different longitudinal propagation velocity in each of the regions, the plurality of regions comprising:
• a central excitation region with a first longitudinal velocity;
• inner edge regions flanking the central excitation region on both sides, wherein a second longitudinal velocity in the inner edge regions is higher than the first longitudinal velocity of the central excitation region;
• outer edge regions flanking the inner edge regions, wherein third longitudinal velocity in the outer edge regions is higher than one of the first longitudinal velocity in the central excitation region or the second longitudinal velocity in the inner edge regions;
• regions of the busbars flanking the outer edge regions, wherein a fourth longitudinal velocity in the regions of the busbars is lower than the third longitudinal velocity in the outer edge regions.