Dispersion of Surface Elastic Waves Produced by a Conducting Grating on a Piezoelectric Crystal

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Abstract
The dispersion relation for surface elastic waves propagating under a thin metallic grating on the basal plane of a hexagonal piezoelectric crystal is investigated theoretically. Purely reactive loads are assumed connected between adjacent electrodes of the grating. The effect of mass loading due to the grating is neglected. The presence of the grating imposes periodic boundary conditions on the piezoelectric fields associated with the surface wave. The resulting boundary‐condition problem is solved to obtain the dispersion relation for surface elastic waves. For a material with a large electromechanical coupling coefficient an inductance connected between adjacent electrodes can cause a large reduction in the phase velocity of the surface wave. (For example, in PZT‐4, this reduction is about 10%.)