8E-2 Accurate FEM/BEM Modeling of SAW Devices Coated with Dielectric Layers

8E-1 A Technique for P-Matrix Computation by Periodic FEM/BEM Analysis

“…Although it is a usual practice to modify the Green function so as to include 1051-0117/07/$25.00 ©2007 IEEE 2007 IEEE Ultrasonics Symposium the effect of electrostatic potential above the substrate, the functionG ij appearing in the above equation is not modified in such a way. Instead, the equation for ϕ is treated in the FEM discussed later [13]. In a periodic structure with period p, the range of integral can be divided into finite intervals of length p. The fieldsũ i andt i may be defined for each direction of propagation, ±x, and it is denoted ast ± i .…”

“…To be specific, we consider the case where the fields u i and ϕ are expressed by linear combinations of known functions on the periodic boundaries. As for the boundaries between the FEM and BEM, which are defined as z = const., the same treatment as in [13] is applied. We assume that the fields on the periodic boundaries can be expressed as…”

“…Then, the FEM equation (20) may be divided into two sets of equations [13]. The first set is for unknown variables of mechanical displacement, electrostatic potential in the dielectric region, and the mode expansion coefficients, while the second set is for electrostatic potential in the electrode region.…”