The properties of acoustic surface waveguides are reviewed, with particular reference to topographic structures in which guiding is achieved by drastic deformation of the substrate surface. A numerical technique, capable of computing efficiently and with high accuracy the mode spectrum of an anisotropic piezoelectric heterogeneous waveguide of arbitrary cross section, is described. Characteristics of both the ridge guide and the recently discovered wedge waveguide are discussed in some detail. Techniques for the fabrication of and transduction onto acoustic surface waveguides are discussed, and a preliminary assessment is made of potential linear and nonlinear waveguide applications. A number of experimental devices are described.

Acoustic surface waveguides - Analysis and assessment

A review is presented of the current state of knowledge concerning waveguiding structures for acoustic surface waves. The stress is on the various types of waveguide and their properties, in order to provide a guide for the applications-oriented engineer. Related matters which are treated more briefly include the reasons for using waveguides, and some applications, both actual and potential.

Waveguides for acoustic surface waves: A review

A finite element method for the analysis of the mode spectrum of an anisotropic piezoelectric elastic wave- guide with arbitrary cross section is described. An assessment of the accuracy is given and the method is then used to com- pute the modes of a few typical waveguide structures.

Finite Element Analysis of Piezoelectric Elastic Waveguides

Motivated by recent developments in acoustic surface waves, a new approach is presented for the systematic analysis and description of acoustic wave phenomena in isotropic solids. This approach employs certain microwave network techniques developed in the context of electromagnetic waveguides. Acoustic wave structures are viewed as being composed of constituent waveguide regions coupled by junctions or ending in terminations; the waveguide regions are described in terms of equivalent transmission lines and the junctions or terminations by lumped equivalent networks. These transmission lines and equivalent networks contain electrical symbols and are cast into pictorial forms familiar in electrical engineering, but they represent purely acoustical quantities and effects. A rigorous transmission-line formalism is presented for acoustic wave propagation in uniform isotropic regions, which takes account of the translational invariance, reflection symmetry, and power orthogonality of the modal fields. This formalism is much more than a rephrasing of acoustic wave phenomena in terms appealing to electrical engineers; it forms the basis for a rigorous and practical procedure for solving complicated acoustic wave problems, and it yields pictorial insight into wave interactions. Despite its recent development, the method has already been applied successfully to several problems of current interest.

http://ieeexplore.ieee.org/iel5/5/31163/01450879.pdf

A microwave network formalism for acoustic waves in isotropic media

Several recent analyses of the flexural mode on a ridge of semi-infinite height (plate edge) contain results which are inconsistent and generally limited in range. We present accurate theoretical calculations, and a set of measurements which agree very well with them, and we compare our results with the earlier ones. We also give a simple model which yields other wave properties (such as the vertical decay rate), indicate and verify quantitatively the wave behaviour at high frequencies, and show the relation between this wave type and the usual flexural mode on a ridge of finite height.

Acoustic flexural mode on a ridge of semi-infinite height

A microwave-network approach is used to obtain an approximate but simple dispersion relation for the ‘flexural’ mode of the ridge waveguide. The propagation characteristics calculated from this relation compare well with experimental data over a wide frequency range.

Simple equivalent network for the flexural mode of the ridge guide for acoustic surface waves

Ahfruct-The microwave network approach to the solution of guided acoustic wave problems was applied in Paper I to two examples of the class of flat overlay guides: the strip and the slot guides. In this paper, the methods are applied to two different rectangular ridge StNChIeS, the well-known topographic ridge guide and the newer overlay ridge guide. In contrast to the flat overlay guides, for which good analytical results were previously available, no other analytical results have been published for the ridge guides which furnish good accuracy (although excellent numerical methods have been described). In addition, little information is available elsewhere on the pseudo-Rayleigh mode of the ridge guides, which is treated here in detail, and the overlay ridge structure itself is a new one whose properties are not yet appreciated. N THE COMPANION paper [l81 , a microwave network approach was presented for the analysis of waveguides for acoustic surface waves. The philosophy underlying this new approach was discussed, the basic features of the method were presented, and the method was applied to two examples of flat overlay waveguides, the strip and the slot guides. In the present paper, this method is applied to a different class of waveguides: rectangular ridge guides. The rectangular ridge waveguides themselves are of two types: the topographic ridge guide, for which the ridge and the substrate are composed of the same material, and the overlay ridge guide, in which the ridge is comprised of a material different from that of the substrate. The two structures are shown in Figs. l(a) and l(b). Both of these ridge guides are fundamentally different from the strip and slot guides, which appear respectively in Figs. l(a) and l(b) of Paper I. In the latter two guides, thin platings are employed to perturb the Rayleigh mode of the substrate, with the result that almost all of the energy in the waveguide mode resides in the sub

Microwave Network Analyses of Surface Acoustic Waveguides - II. Rectangular Ridge Guides

An approximate but simple dispersion relation is derived for the pseudo-Rayleigh mode of the ridge waveguide. The wave is essentially nondispersive and its phase velocity is slightly lower than that of the Rayleigh wave.

Propagation characteristics of the pseudo-Rayleigh mode of the ridge guide for acoustic surface waves

Using a microwave network approach, approximate but simple dispersion relations are obtained for the "flexural" and "pseudo- Rayleigh" modes of the ridge waveguide. The propagation characteristics calculated from the relation for the " flexural" mode compare very well with experimental data over a wide frequency range; no accurate measurements are presently available for the "pseudo-Rayleigh" mode.

S. Markman

Papers

Simple equivalent network for the flexural mode of the ridge guide for acoustic surface waves

Microwave Network Analyses of Surface Acoustic Waveguides - II. Rectangular Ridge Guides

Propagation characteristics of the pseudo-Rayleigh mode of the ridge guide for acoustic surface waves

Propagation Characteristics of the Ridge Waveguide for Acoustic Surface Waves