Analysis of SAW propagation in gratings on ZnO/diamond substrates
The space harmonic method is used to analyze surface acoustic wave (SAW) propagation under an infinite periodic metal grating on ZnO/diamond composite layered substrates. Dispersion properties for shorted and open gratings are derived as a function of the thickness of the grating electrodes. From these dispersion relations, the coupling of modes (COM) parameters are derived. Energy profiles inside ZnO/diamond show that the energies contained in each of the ZnO and diamond layers are of the same order when the thickness of the ZnO layer is P//spl pi/r (P=grating period) and that the energy is contained within two wavelengths below the ZnO/diamond interface.
Surface Acoustic Wave Propagation Characteristics and Temperature Effects on Quartz under Periodic Aluminum Structure
In communication applications, surface acoustic wave (SAW) devices should have excellent temperature stability. For this purpose, a numerical procedure for analyzing the Rayleigh SAW propagation and temperature effect was established in this work. The theoretical method used here is the space harmonic method (SHM). The theoretical analysis showed a slightly enhanced reflectivity for the open grating and presented the centers of transduction and reflection as separate at a spatial distance of λ0/4. The computational frequency responses of a two-port resonator were similar to the experimental data. The temperature characteristics of quartz under aluminum grating were also studied in this work. The cut angle of the quartz with zero temperature coefficient of frequency (TCF) decreased with increasing aluminum grating thickness. The coupling-of-modes (COM) parameters of quartz with zero TCF were calculated.
S.A.W. reflecting arrays
It is shown that metal surface-acoustic-wave reflecting arrays on piezoelectric substrates with a range of ratios t of electrode width to period can be modelled by a cascade of equal-length transmission-line sections. Measurements were made on short- and open-circuited arrays with various t ratios; impedance ratio r and average velocity data are presented against t.