High efficiency elastic convolver using KNbO/sub 3/ substrate

Elastic convolvers are very important for signal processing devices of the spread spectrum communication (SSC) systems. The better efficient convolvers are required for the application for the spread spectrum and next stage communication systems. A high value of coupling coefficient is very important for wideband and high efficiency SAW devices such as SAW convolvers. Potassium niobate (KNbO/sub 3/) has large piezoelectric constants and very large electromechanical coupling coefficient (K/sup 2/) of 0.53 for the surface acoustic waves which is about 10 times larger than that of LiNbO/sub 3/. Therefore the high efficient elastic SAW convolvers using KNbO/sub 3/ substrates are expected. In this paper, the rotated 60/spl deg/ Y-cut, X-propagating KNbO/sub 3/ substrates are used for a convolver. The experimental results show that the efficiency of the convolver using 60 /spl deg/Y-X KNbO/sub 3/ is 15 dB higher than of he convolver using Y-Z LiNbO/sub 3/.