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

Abstract

Previous analysis of the equivalent circuit for the ultrasonic delay line wag 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 BaTi03 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 bandwidth to be expected as the impedance of the delay medium is increased. The increase in bandwidth resulting from symmetrical loading of the transducers is also evaluated. Modifications to the equivalent circuits for the case of BaTi03 ceramic transducers are considered. Theoretically losses can be reduced to 10 db or less using the ceramic transducers with a vitreous silica medium. The bandwidth is slightly less than for quartz crystal transducers. However, by utilizing higher impedance materials,. bandwidths approaching 100% should be achieved.