Coordinate-free, frequency-independent universal functions for BAW analysis in SAW devices

We critically consider the boundary element method (BEM) as applied to SAW devices and describe a convenient way for increasing the accuracy of the numerical data, while significantly reducing the required computer resources. We construct appropriately defined frequency-scaled Green´s functions and show that a function A(|X|) exists such that, say, for the interaction between the k^th and l^th substrips in BEM applications the relationship A_kl=A(|a_kl|)-A(|b_kl|)-A(|c_kl |)+A(|d_kl|) holds true, even for the more complicated self-action elements (k=l). The various arguments of the function A(|X|) are related to the geometrical data of the aforementioned substrips. The coordinate-free, frequency-independent universal function A(|X|) merely involves the associated Green´s functions, and thus can be tabulated for any material and cut only once. We validate our approach by comparing simulation results with experimental data