Title :
Three necessary conditions for the validity of the Fresnel phase approximation for the near-field beam pattern of an aperture
Author :
Ziomek, Lawrence J.
Author_Institution :
Dept. of Electr. & Comput. Eng., US Naval Postgraduate Sch., Monterey, CA, USA
fDate :
1/1/1993 12:00:00 AM
Abstract :
A simple, straightforward derivation of three necessary conditions that define the region of validity for the near-field directivity function (beam pattern) of an aperture (array) is presented. The derivation of all three criteria is based on determining what conditions must be satisfied in order to obtain a valid Fresnel approximation of the time-independent free-space Green´s function. Comparisons with other near-field conditions in the literature are made
Keywords :
Green´s function methods; acoustic arrays; acoustic signal processing; underwater sound; Fresnel phase approximation; aperture; array; near-field beam pattern; near-field directivity function; time-independent free-space Green´s function; underwater sound; Acoustic beams; Acoustic diffraction; Apertures; Optical arrays; Optical diffraction; Phased arrays;
Journal_Title :
Oceanic Engineering, IEEE Journal of
