Planar harmonic Green´s function, its papal approximation and applications

A planar harmonic Green´s matrix function makes the relationship between all harmonic wave field components involved in boundary conditions on a piezoelectric halfspace. This is sufficient characterization of a substrate in most boundary-value problems concerning SAW devices, it can also be exploited in analysis of layered elastic structures. A papal approximation to this function is introduced that is physically correct in finite domains of a wave number spectral variable around the cut-off wave numbers of bulk waves. Green´s functions have branch points there, and these domains are most important in many applications.