Talk:Surface acoustic wave

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Complete diagram of SAW Filter and working, Construction of SAW. Thank You

[edit] "Acoustic" Wave

Not to be a pedant but I have a question about the nature of the mechanical waves used / detected in these devices. In complete generality, linear elastic media exhibit waves made up of dilatational and shear strain fields and, at some boundaries and discontinuities, combinations of the two. Linear elastic fluid waves are dilatational only, and it is these that are usually referred to as "acoustic" by theoretical mechanics types. However, for the purposes for which SAW devices are used, it may be true that the shear vs. dilation distinction is irrelevant, and that any & all mechanical waves in the device are considered "acoustic" to distinguish them from the EM phenomenon.

Is that the case?

Correct, acoustic wave generally refers to a traveling mechanical disturbance through a medium. However in the case of most SAW devices a piezoelectric effect exists which means that there will also be a corresponding electric field traveling with the wave (this phenomena cannot be neglected as it drastically effects the waves characteristics). A SAW is a truely separate mode from bulk waves, and is generally considered a SAW if energy is traped at the surface boundary and the wave exists in the far field (ironically the most common "SAW" device on LiTaO3 found in cell phones utilizes a wave which leaks energy to the bulk and does not exist far field, this wave is called a "psuedosaw"). As you mention these waves may have any combination of shear and longitudinal components (in crystals these modes depend on crystal orientation). If you want to know more obtain a copy of "Surface Acoustic Wave Devices for Signal Processing" by Morgan, it is an excellent introductory text.

Shouldn't Surface Acoustic Wave Device be given its own article and this article refer to the physical SAW phenomena only? This article would then have links to related ones on SAW devices, earthquakes, nondestructive evaluation etc? There are many volumes written on both of these topics.

[edit] update

removed a commercial link and added a link to a whole explanation of the SAW filters--bloublou 08:36, 31 August 2006 (UTC)