Accession Number : AD0672364

Title :   A SERIES EXPANSION METHOD FOR THE PREDICTION OF THE FAR FIELD FROM NEAR FIELD MEASUREMENTS,

Corporate Author : PARKE MATHEMATICAL LABS INC CARLISLE MASS

Personal Author(s) : Butler,John L.

Report Date : JUL 1968

Pagination or Media Count : 55

Abstract : A series expansion method for determining the far field from near-field measurements of coherent and partially coherent sound fields is described. The method is based on a series expansion of the solution in spherical wave functions truncated to include only the number of terms equal to the number of near-field measuring points. The expansion coefficients may be evaluated through a matrix inversion for near field measuring points at any reasonable location. A comparison of exact and predicted far fields is presented for some simple source distributions, and it is shown that good results can be obtained even for measuring surfaces that do not completely enclose the source. (Author)

Descriptors :   (*ANTISUBMARINE WARFARE, *UNDERWATER SOUND), UNDERWATER OBJECT LOCATORS, PHASED ARRAYS, HYDROPHONES, WAVE FUNCTIONS, SONAR TARGETS, MATHEMATICAL ANALYSIS, SOUND TRANSMISSION

Subject Categories : Undersea and Antisubmarine Warfare
      Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE