Patent ID: 6534896
Filing Date: 2003-03-18
Classification: H03H

Abstract:
A SAW (surface wave) device comprising an inter-digital transducer on a substrate of piezoelectric material, the transducer comprising a plurality of repeated groups each of at least five electrodes, the electrodes of each group having a predetermined polarity sequence, the groups being arranged along a length of the transducer to operate coherently for SAWs at a signal frequency of the transducer, the signal frequency having a spatial harmonic relationship to, and not being the same as, a SAW frequency corresponding to a pitch of said electrodes, wherein the transducer further comprises at least one reflector for reflecting SAWs at the signal frequency, the reflector being positioned along the length of the transducer adjacent to said groups of electrodes to provide constructive interference of SAWs at the signal frequency in one direction along the length of the transducer and to provide destructive interference of SAWs at the signal frequency in an opposite direction.