| 摘要 |
PURPOSE:To form a beam covering an azimuth angle of 360 deg. in total by erasing the imaginary azimuth of a zero point of a cardioid directivity toward an azimuth symmetrical to the array axis of a shaping azimuth. CONSTITUTION:In case of an output at a terminal Y with the shaping azimuth 330 deg., a circular cone-shaped directivity in 30 deg. and 330 deg. directions is formed normally by the symmetry of the array, since signals for the 30 deg. direction of the zero point of the cardioid directivity are collected and shaped, the directivity pattern is obtained, where the directivity is directed toward the azimuth of 330 deg. only. In case of an output at a terminal Y1 in the shaping azimuth of 180 deg., when the interval between receivers is close to a half wavelength of a sound wave, the imaginary azimuth is caused in the direction of 0 deg., and signals where zero point of the cardioid directivity is directed toward 0 deg. are collected and shaped so as to obtain the directivity pattern where the directivity is directed only toward 180 deg..
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