Patent ID: 6480076
Filing Date: 2002-11-12
Classification: H03H

Abstract:
A surface acoustic wave transducer having a transduction length measured in wavelengths, comprising:a piezoelectric substrate; a pattern of electrodes formed on a surface of the substrate in the transduction length, the pattern of electrodes being formed of M uniform-width, uniformly spaced, single-level interdigitated electrodes per each N&lgr; of the transduction length, adjacent electrodes having a center to center spacing of N&lgr;/M; a first reflective structure formed in a first gap located between two adjacent electrodes within a first N&lgr; of the transduction length for creating a first finite localized surface acoustic wave reflection function in both magnitude and phase; and a second reflective structure formed in a second gap located between two adjacent electrodes within a second N&lgr; of the transduction length for creating a second finite localized surface acoustic wave reflection other than zero in both magnitude and phase, the combined first and second finite localized reflection functions of all transduction lengths forming a desired continuous reflection function within the transducer; and wherein the first reflective structure comprises the substrate surface at the first gap having a plurality of randomly distributed recesses formed therein, each of the randomly distributed recesses having a predetermined depth equal to the depth of each other randomly distributed recess.