Broadband Constant Beamwidth Acoustical Arrays

摘要

The beamwidth of most directional receivers decreases with frequency. If broadband signals are used and accurate pointing is not maintained, spectrum shape is not preserved. Constant beamwidth arrays to prevent this problem are proposed here. When the output of an array is combined with the output of a half scale model of the array through the proper filters, constant beamwidth over an octave frequency range results. This process is continued to provide the desired bandwidth. A three element-two octave microphone array is described and its characteristics presented. Although the correct filters were not available, only plus or minus 8 degrees variation in beamwidth from 500 Hz to 2 KHz was achieved. Further study is recommended and application to many systems is suggested. (Author)