PURPOSE: To reduce the loss and to widen the band by specifying the relation between the center distance between opposite electrode fingers and the wavelength of a surface acoustic wave and the relation between the characteristic impedance discontinuation quantity between the surfaces of an electrode finger part and a no-electrode-finger part and the logarithm of interdigital electrodes for input and output.
CONSTITUTION: The peak of an internal reflected wave is made coincident with the reflected wave peak between input and output interdigital electrodes 1 and 2. Namely, an inequality I holds, where (n) is a natural number including 0 and λ is the wavelength of the surface acoustic wave. Further, when N1 and N2 couples of input and output interdigital electrodes 1 and 2 are provided, let N1 and N2≥n/ and N2≥3/2N1, where is the discontinuation quantity of the characteristic impedance between the surfaces of the electrode finger part and no-electrode-finger part of the interdigital electrodes, and an internal reflected wave is utilized. Consequently, the internal reflected wave peak P1 of the interdigital electrodes 1 and 2 and the reflected wave peak P2 between the input and output interdigital electrodes 1 and 2 are made coincident with each other to reduce the loss and widen the band.
HOSAKA NORIO
YAMADA JUN
SHIBA TAKASHI
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| JPS58141023A | 1983-08-22 | |||
| JPS61192112A | 1986-08-26 |