FFT-based analysis of periodic structures in microacoustic devices

Abstract

Abstract-Periodic structures utilized as transducer or reflector elements play an important role in microacoustic wave devices. Such structures can be described using approximate analytical models. However, to obtain the accuracy required for reliable device simulation, numerical methods have to be employed. In this contribution, we present an efficient numerical approach to calculate the dispersion curves associated with microacoustic modes propagating in periodic structures; the method is demonstrated for the case of Love wave modes. The computational efficiency is related to the utilization of the FFT algorithm in a hybrid Method of Moments (MoM) /Mode-Matching analysis. From the obtained dispersion curves, characteristic parameters such as the stopband width can be obtained which can be used in a coupling-of-modes (COM) model of the structure.

Spectral analysis based on fast Fourier transformation (FFT) of surveillance data: the case of scarlet fever in China

“…As spectral analysis is becoming increasingly indispensable in biomedicine and epidemiology [11][12][13], some barriers to this method have been noted that may affect its application. First, some spectral approaches are too empirical to be appropriate.…”

Efficient semi-numerical analysis of acoustic sensors using spectral domain methods—a review

“…This can be performed efficiently, by eliminating singular contributions due to first order poles of the form A x∞,i /(k x − k x∞,i ) from Green's function and treating them separately in an analytic manner, whereas the well-behaved remainder can be integrated numerically. If the basis and testing functions are chosen to be of the same shape but with shifted centers, respectively, e.g., as series of laterally shifted rectangular functions, the evaluation of the integral can be efficiently approximated using the fast Fourier transform (FFT) algorithm yielding all required matrix elements from a single FFT evaluation (see, e.g., [22]).…”

“…For instance, the mass-loading created by the IDT-fingers, which was neglected in the calculations described above, represents such an elastic obstacle. As an example for such structures, in [22] the modeling of periodically placed elastic blocks on top of a Love mode waveguide was described by introducing a coupling of the spectral domain method with an eigenmode expansion for the vibrational fields in the blocks.…”

“…This method is quite common and has also been considered, e.g., in [23,24]. In [22], the approach is illustrated for the simplified case of a purely elastic problem involving isotropic media.…”