PURPOSE: To remarkably suppress an end face reflection signal of an acoustic wave, by shifting a position of a propagation path end part, by ≥1 stage by width of λ/4×N(N=1,3,5∼, and λ denotes the wavelength of the acoustic wave), and also setting the overall length of the propagation path end part to half of the whole.
CONSTITUTION: An electric signal is converted to an acoustic wave by the first reedlike electrode 2 or 3, and the surface acoustic wave is converted to the electric signal again by the second bamboo blind-like electrode 3 or 2. A position of a propagation path end part of the acoustic wave is formed by shifting at least 1 stage by width of λ/4×N (N=1,3,5∼, and λ denotes the wavelength of the acoustic wave), and the overall length of the propagation path end part which has been shifted and formed is set to 1/2 of the whole. When each half of the propagation path end part for reflecting the acoustic wave is shifted by λ/4× N from each other, reflected waves from the respective end parts negate each phase, no reflection signal appears in the second reedlike electrode, and a satisfactory frequency characteristic of only a main signal can be obtained.
YAMADA JIYUN
KISHIMOTO SEIJI
YANAGIHARA HITOSHI
HAZAMA TAKESHI
