Wideband low triple transit delay line
AssigneeWestinghouse Electric Corp.
InventorsRobert A. Moore, Robert N. Sundelin
Life of this patent
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Abstract
Electroacoustic apparatus is described incorporating a substrate having a transducer on an upper surface and a transducer on a lower surface positioned for receiving bulk acoustic waves; substrate taper along with transducer geometry are combined to provide bulk acoustic signals in the near zone or Fresnel zone which provide for phase and amplitude cancellation of a triple transit signal. The invention overcomes the problem of spurious triple transit signals in bulk mode acoustic delay lines for input signals having a wide bandwidth, such as an octave, and where the delay times are short such that the bulk acoustic wave remains in the near zone or the transition region between the near zone and far zone.
Claims16
Electroacoustic apparatus for delaying signals and for providing wideband triple transit suppression about a predetermined center frequency comprising:
- a substrate having an upper and lower surface, said substrate comprised of material suitable for propagating bulk acoustic waves,
- a first transducer mounted on said upper surface for generating bulk acoustic waves toward said lower surface,
- a second transducer mounted on said lower surface and positioned for receiving bulk acoustic waves from said first transducer,
- said first and second transducers having a plurality of spacings between each other, and having a maximum spacing between themselves which is less than 2d.sup.2 /3.lambda. where d is the maximum width of one side of said first transducer and .lambda. is the wavelength of the ultrasonic elastic wave in the transmission medium at said predetermined center frequency.
Dependencies are inferred from the claim text.