Elastic surface wave lines

Examples of the use of surface waves, especially Rayleigh acoustic waves, to delay a signal and match a filter to a coded signal are discussed. The basic principles of surface wave generation and propagation are reviewed. The characteristics of delay lines with constant and frequency-variable delays are presented. Research in the field of signal storage is summarized. Special attention is given to the technique whereby an electrostatic image of the signal is formed on a piezoelectric substrate by secondary electrons which are displaced by a brief bombardment of primary electrons and distributed along the electrical potential associated with the wave.