Abstract: A surface acoustic wave delay line uses a closed loop principle with separate input and output transducers side by side. 3dB Multistrip couplers are introduced to achieve substantially 100% transfer for surface acoustic wave energy from the propagation path associated with the input transducer to the propagation path associated with the output transducer. Several such delay lines can be formed on a single cylindrical body of piezoelectric material and these can then be cascaded with intermediate amplification to form a long delay or a tapped delay.

Abstract: This invention comprises in combination a body of piezoelectric material, means for propagating an acoustic wave in a first mode, means for converting a portion of the acoustic wave energy into an acoustic wave in a second mode, a resonant structure in which the acoustic wave energy in the second mode is resonant, means for reconverting the acoustic wave energy in the second mode into surface acoustic wave energy in the first mode, means for providing a predetermined phase shift of the reconverted acoustic wave energy relative to the original propagated acoustic wave energy, and means for recovering the combined acoustic wave energy of the original and phase shift reconverted acoustic wave energies as an electric output signal.