Bulk waves radiated from an interdigital metallic transducer deposited on an anisotropic substrate

The whole acoustic field emanating from a metallic interdigital transducer (IDT) deposited on an anisotropic half-space is computed. Extending the classical Lamb approach, it is shown that the field can be expressed by an integral whose singularities give rise to both Rayleigh surfaces waves (SAWs) and well collimated bulk waves (BAWs). For a Y-cut, Z-propagation quartz crystal a horizontal shear wave is excited; it is shown that the orientation and width of the main lobe can be chosen by changing the frequency.