Accession Number : AD0718322

Title :   A New Approach to Superdirective Arrays.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB ORLANDO FLA UNDERWATER SOUND REFERENCE DIV

Personal Author(s) : Robinson,A. Z.

Report Date : 05 JAN 1971

Pagination or Media Count : 31

Abstract : The concept of defined nulls in the directional response of arrays and the introduction of electrical delays to achieve the desired placement of the nulls provide a new approach to acoustical superdirective arrays. The shading that results is a variant of binomial shading in that the number of times a given element contributes to the array output is determined by the appropriate binomial coefficient, but the signal from the element undergoes a possibly different electrical delay each time the element contributes. For an end-fire condition, the maximum array gain (assuming isotropic noise) is equal to the square of the number of elements in the array. The methods used yield results for three- and five-element broadside arrays that are equivalent to those obtained earlier by R. L. Pritchard. The type of array described responds to a higher order gradient of the pressure field rather than to the pressure field itself. A digital method for implementation of such an array is presented. (Author)

Descriptors :   (*UNDERWATER SOUND, SOUND TRANSMISSION), (*SONAR ARRAYS, DESIGN), UNDERWATER SOUND GENERATORS, TRANSDUCERS, RESPONSE, MATHEMATICAL MODELS

Subject Categories : Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE