Title :
Excitation of higher order modes in Lamb wave delay lines
Author :
Jin, Y. ; Joshi, S.G.
Author_Institution :
Dept. of Electr. & Comput. Eng., Marquette Univ., Milwaukee, WI, USA
Abstract :
The excitation of higher-order ultrasonic Lamb wave modes by an interdigital transducer deposited on a piezoelectric plate is investigated both theoretically and experimentally. It is found that depending on the value of the ratio h/λ (h=plate thickness, λ=acoustic wavelength), a number of higher-order modes can be efficiently excited. The phase velocity of higher-order modes is greater than the surface acoustic wave (SAW) velocity, while their group velocity is lower than that of the SAW. Thus, these modes have a higher resonant frequency and also a longer time delay than the surface acoustic wave. It is found that in acoustically thin plates (h/λ<1) the interdigital transducer (IDT) can efficiently couple to higher-order Lamb waves modes having resonant frequencies greater than ten times the fundamental SAW resonant frequency
Keywords :
surface acoustic wave devices; surface acoustic waves; ultrasonic delay lines; Lamb wave delay lines; excitation; higher-order ultrasonic Lamb wave modes; interdigital transducer; piezoelectric plate; resonant frequency; Acoustic waves; Delay effects; Delay lines; Electric potential; Equations; Green´s function methods; Piezoelectric transducers; Resonant frequency; Surface acoustic waves; Surface waves;
Conference_Titel :
Ultrasonics Symposium, 1992. Proceedings., IEEE 1992
Conference_Location :
Tucson, AZ
Print_ISBN :
0-7803-0562-0
DOI :
10.1109/ULTSYM.1992.275976
