| 摘要 |
PURPOSE:To make uniform the horizontal plane and vertical plane directivity angle frequency characteristics, by the double construction of the inner wall providing a number of holes being LPF in straight line and the external wall of exponential horn shape, as the upper and lower wall at the opening side of radial horn. CONSTITUTION:As to the horizontal plane directivity angle characteristics similarly operated as conventional radial horn, since the side wall of the radial horn 4 is of straight line, the directivity characteristics almost equal to the horn horizntal opening angle alpha is shown. As to the vertical plane, at the horn throat section, exponential change is caused, and the horn inner walls 5, 5' are made to straight line at the horn opening and the opening angle of the inner walls 5, 5' is taken as beta to obtain the directivity angle characteristics so that directivity angle is uniform at middle and high frequencies. If the horn is operated at te low band, the sound is passed with LPF providing holes 7 on the inner walls 5, 5', the similar operation as the radial horn determined with the external walls 6, 6' is made and operation is made without lowering the low band acoustic radiation resistance. In case of operation more than the middle band, the holes 7 block the passage of sound to show the horn directivity angle characteristics determined with the inner walls 5, 5' and the horn side wall. |
