Interest in surface acoustic waves has increased year by year since Lord Rayleigh first found their existence. These waves are of modes of propagation of elastic energy along the free surface of an infinite half-space in which the associated energy density is concentrated within a distance of the order of a wavelength below the free surface. Current interest in surface acoustic waves is being intensified by their potentialities in signal-processing devices. This is, partly, because the devices can be made with a concomitant size reduction corrresponding to the ratio of the velocity of the acoustic waves to that of the electromagnetic waves, and because such waves can interact with the adjacent media on the propagation surface. In this review the research trends of the surface acoustic wave devices are described.
