Although the existence of the surface acoustic wave (SAW) was first dis-
cussed in 1885 by Lord Rayleigh [1], it did not receive engineering
interest for a long time. In 1965, the situation changed dramatically.
White suggested that SAWs can be excited and detected efficiently by
using an interdigital transducer (IDT) placed on a piezoelectric
substrate [2]. This is because very fine IDTs can be mass-produced by
using photolithography, which has been well developed for semiconductor
device fabrication, and proper design of the IDT enables the
construction of transversal filters with outstanding perfor- mance.
Then, in Europe and America, a vast amount of effort was invested in the
research and development of SAW devices for military and communication
uses, such as delay lines and pulse compression filters for radar and
highly stable resonators for clock generation. Research activities are
reflected in the various technical papers represented by special issues
[3-5] and proceedings [6]. The establishment of design and
fabrication technologies and the rapid growth of digital technologies,
represented by the microcomputer, meant that the importance of SAW
devices for the military decreased year by year and most researchers in
national institutions and universities left this field after reductions
or cuts in their financial support. Then the end of the Cold War forced
many SAW researchers in companies to do so, too.