GB1425849A - Tapped praetersonic bulk delay line - Google Patents

Abstract

1425849 Electro-acoustic delay lines WESTINGHOUSE ELECTRIC CORP 23 May 1973 [28 June 1972] 24589/73 Heading H3V A praetersonic, i.e. high frequency ultrasonic, delay line comprises a transducer 12, Fig. 1, which launches bulk waves into one end of a piezoelectric body 10 having spaced output devices. As shown, these comprise tap loops 24, 26 extending round the body 10 and connected to terminals 28. Absorber material 14 may be provided at the other end of the body 10. Earthed strips (30, Fig. 2, not shown) may be provided on the body to electrically shield the loops 24, 26. With a plurality of variablyspaced taps a coded delay line may be provided. In the modification of Fig. 3, a piezoelectric layer 32, e.g. of LiNbO 3 , is provided on a substrate 34, e.g. of fused quartz, having an earthed metallized surface 36. The output devices are interdigitated electrode pairs 40, 42. In a further modification, (Fig. 4, not shown) layers of non-piezoelectric material (50, 52), such as ruby, sapphire or silicon, are provided on opposite surfaces of a fused quartz block and then layers of piezoelectric material (51, 53) are deposited. Bulk waves launched into the non- piezoelectric layers by respective transducers 58, 60 are coupled into the piezoelectric layers which have as output devices spaced strips 62 thereon. Interdigitated electrodes (Fig. 5, not shown) which may be used as an output device, have fingers which are closer together at one end than the other so that the delay time increases with frequency.