| 摘要 |
PURPOSE:To easily form a uniformized electrode pattern width. by setting the repeating pitch of pairs of electrodes to a length which is a specific times longer than the wavelength of a surface wave. CONSTITUTION:A unidirectional electrode is composed of cyclically arranged electrodes 31, 32, and 33 having three-phases polarities R, S, and T and each pair of electrodes 34a, 36a, 34b-. The repeating pitch 35 of each pair of electrodes is set to a length which is (integer+1/2) times the wavelength of a surface wave. Namely, the width of a shield electrode finger 45 inserted between the paired electrodes 34a and 36a is set to lambda/2 which is equal to the width of shield electrode fingers 42 and 43. Moreover, each polarity group electrode 61a, 61b, 62a, and 62b is composed of three electrode fingers, the polarity group electrodes 62a and 62b belonging to the paired electrodes 36a are arranged to have the opposite phase with respect to the polarity group electrodes 61a and 61b belonging to the paired electrodes 34a and the T-porality shown by 33. |
