| 摘要 |
PURPOSE:To prevent disturbance of measurement otherwise caused by a side lobe of a received output, by making directivity patterns of first and second plane vibrators almost coincide with each other in the direction of a main lobe to differentiate the position of the side lobe of the second vibrator in a range where a side lobe exists with a relatively large intensity of the first vibrator. CONSTITUTION:Directivity patterns (a) and (b) of a vibrator 3 for transmission and a vibrator 7 for reception coincide with each other in the direction of a main lobe and the direction of the minimum value between the main lobe of the pattern (b) and a first side lobe is fixed to the direction of the maximum value of the first side lobe of the pattern (a). With such an arrangement, when an ultrasonic wave which is transmitted from the vibrator 3 and reflected on an object 5 is received with the vibrator 7, a synthetic pattern (c) is obtained and as the direction of the main lobes coincide with each other, it is kept at a fixed level. A side lobe level of the synthetic pattern (c) is suppressed in a relatively high low-order side lobe thereby preventing disturbance of measurement otherwise caused by the side lobe of a received output. |
