CRYOGENIC HYPERSONIC DELAY-LINE FOR MILLIMETER-BAND SIGNALS

A cryogenic hypersonic delay line (HDL) for pulse signals in the 8-mm band is described. Its operation is based on conversion of these signals to longitudinal hypersonic waves, which are propagated in a sapphire acoustic line. Conversion is preformed by means of a textured piezoelectric film of zinc oxide with an aluminum sublayer. The microwave electric field is concentrated in the film using a wideband slot resonator, which provides a high conversion factor (on the order of 10(-3)) over a wide range of frequencies. The acoustic line of the HDL, along with the transducer and slot resonator, is cooled by liquid helium to 4.2 K. For a 3.2-mu-sec delay, the total losses of a pulse signal with a duration of 0.5-mu-sec at a frequency of 35 GHz are not more than 70 dB with a bandwidth of 1.5 GHz.