(P)SAW in a grating

This is an original work in the sense that you won't find an equivalent program elsewhere! Please refer to the following paper for some explanations on the problem and the methods. The algorithms used are the same for SAW's and PSAW's. They are based on the original FEM/BEM programs of Pascal Ventura, extended to include slanted propagation in infinite periodic IDT's.

The quality of the fit can be monitored by plotting the files spy.dat and fit.dat which can be chosen (in the Advanced Parameters dialog) to be saved for each run. This functionality is also helpful to choose a correct slowness range for the fit.

The choice is given (in the Advanced Parameters dialog) to consider either a slanted wave in a fixed grating (which is what SlownessBuddy was designed for in the beginning) or to rotate the grating AND the phase angle. This last option is helpful to identify the most interesting propagation angles for a given substrate cut.

The choice is given to estimate either the parameters of the pseudo-pole (i.e. the synchronism slowness, without explicit consideration in the estimation of the reflection coefficient) or the full mixed matrix parameters (as usual with the FEM/BEM method, without the reflection phase).

The model used for mixed matrix parameter estimation is not yet described officially in a document, as it is still under development. It is based on the use of two nearby frequencies, with the result that ambiguities in the estimation are avoided (warning: this is subject to amendments). The basic assumption is that the MM parameters are dependent on frequency, unlike usually assumed. At present, the estimation is excellent for the static capacity, good for the slowness, the attenuation and the reflection coefficient, mediocre for the G parameter (linked to the coupling strength). Other parameters are not given reliably.