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

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)

Document Details

Document Type
Technical Report
Publication Date
Jul 01, 1968
Accession Number
AD0672364

Entities

People

  • John L. Butler

Tags

DTIC Thesaurus Topics

  • Coefficients
  • Far Field
  • Inversion
  • Mathematics
  • Measurement
  • Near Field
  • Spherical Waves
  • Wave Functions
  • Waves

Fields of Study

  • Physics

Readers

  • Calculus or Mathematical Analysis
  • Fluid Dynamics.
  • Plasma Physics / Magnetohydrodynamics