| 摘要 |
PURPOSE:To obtain a unidirectional and wide-band transducer by shifting an electrode part in a surface acoustic wave propagation direction by a quarter as long as the wavelength of a surface acoustic wave having a center frequency. CONSTITUTION:Electrode parts 2 and 3 consists of couples of electrode pieces 6-9 crossing mutually on a piezoelectric material substrate 1. The one-side electrode pieces 6 and 7 are brought into contact with each other along electrode crossing width (b) to be grounded in common, and both the electrode parts 2 and 3 are shifted in a surface acoustic wave propagation direction by a quarter as long as the wavelength of a surface acoustic wave having a center frequency. A phase shifter 4 is connected to the other-side electrode pieces 8 and 9 to give a phase difference for prescribed frequency characteristics. Thus, the phase shifter 4 change phase conditions according to the frequency of an input signal to give a 0 deg. phase differnece to a surface acoustic wave traveling in one direction and a 180 deg. phase difference to each surface acoustic wave traveling in the opposite direction over a wide range. |
