Basic equations
Acoustic components used for filtering

Here we consider a generic stack of infinitely extended layers in the x ₁ and x ₃ directions. We use the axis conventions defined on 2 . This is the coordinate system classically employed in surface wave models: the x ₂ axis is oriented downwards so as not to have to deal with negative coordinates when considering the substrate. Since we are interested in monochromatic plane wave propagation, we assume that all fields possess a spectral harmonic dependence in exp(jω (t - s _< x _< )), with s _<...