| 摘要 |
<p>[PROBLEMS] To provide a boundary acoustic wave device which can attain a sufficiently large electromechanical coupling coefficient K<SUP>2</SUP> while suppressing an increase in conductor resistance even in the case of high frequency. [MEANS FOR SOLVING PROBLEMS] In the boundary acoustic wave device (10), an IDT (13) is arranged between a first medium (11) and a second medium (12), a plane dividing the IDT (13) equally into two in the thickness direction serves as a boundary plane, and, assuming the energy of the boundary acoustic wave on the first medium (11) side from the boundary plane is E1, the energy on the second medium (12) side from the boundary plane is E2, and the energy of the boundary acoustic wave on the first medium (11) side from the boundary plane is E1' and the energy on the second medium (12) side from the boundary plane is E2' under such conditions that the IDT (13) is constituted only of a conductor layer of highest density such that the sound velocity of the boundary acoustic wave when the IDT (13) is constituted is identical to the sound velocity of the boundary acoustic wave when the IDT (13) is constituted using only a conductor layer of highest density constituting the IDT (13), following relation is satisfied; E1/E2>E1'/E2'.</p> |
