Macroscopic Disk Rotation by Means of Surface Acoustic Waves.

It is shown experimentally that a flat piezoelectric disk poled perpendicular to its surface and suspended on a thin thread can be rotated about 50° by two surface acoustic waves (SAWs) intentionally excited with different amplitudes and propagating in the opposite directions. The excitation of such counter-propagating SAWs with different amplitudes is based on the nonsymmetrical interdigital transducer with different angular width electrodes located along the disk radius. The angular width of each of the two electrodes per angular period is not change along the disk radius.

Two-finger (TF) SPUDT cells.

SPUDT cells including two fingers are only known thus far for so-called NSPUDT directions. In that case, usual solid-finger cells are used. The purpose of the present paper is to find SPUDT cell types consisting of two fingers only for pure mode directions.

Analogs of Brewster's angles for surface acoustic waves: the dependence on the strip shape.

The analogs of Brewster's angles for surface acoustic waves (SAW) were found 30 years ago. Considering the reflection of classical Rayleigh waves in an isotropic half-space at oblique incidence by long topographic irregularities of small thickness, such as projections and grooves, it was found by a perturbation method that, independently from the shape of the irregularities, the reflection coefficient is equal to zero for some angle of incidence. The problem was never treated more accurately than by the first order perturbation method using the thickness/wavelength ratio as a small perturbation parameter.

Fast variation method for elastic strip calculation.

A new, fast, variation method (FVM) for determining an elastic strip response to stresses arbitrarily distributed on the flat side of the strip is proposed. The remaining surface of the strip may have an arbitrary form, and it is free of stresses. The FVM, as well as the well-known finite element method (FEM), starts with the variational principle.

Harmonic admittance and dispersion equations--the theorem.

The harmonic admittance is known as a powerful tool for analyzing the excitation and propagation of surface acoustic waves (SAWs) in periodic electrode arrays. In particular, the dispersion relationships for open- and short-circuited systems are indicated, respectively, by the zeros and poles of the harmonic admittance. Here, we show that a strict reverse relationship also exists: the harmonic admittance of a periodic system of electrodes may always be expressed as the ratio of two determinants, which have been specifically constructed to describe the eigen-modes of the open- and short-circuited systems.