Characteristics of Ultrasonic Delay Lines Using Quartz and Barium Titanate Ceramic Transducers

Abstract

Previous analysis of the equivalent circuit for the ultrasonic delay line was applied to quartz crystal transducers and a vitreous silica delay medium. The analysis has been extended to evaluate the use of other materials such as magnesium, aluminum, and steel, and to include BaTiO3 ceramic transducers. Calculations show the decrease in loss to be expected as the impedance of the delay medium is decreased and conversely the increase in band width to be expected as the impedance of the delay medium is increased. The increase in band width resulting from symmetrical loading of the transducers is also evaluated. Modifications to the equivalent circuits for the case of BaTiO3 ceramic transducers are considered. Theoretically losses can be reduced to 10 db or less using the ceramic transducers with a vitreous silica medium. The band width is slightly less than for quartz crystal transducers. However, by utilizing higher impedance materials, band widths approaching 100 percent should be achieved.