Overestimation of On-Axis Power Density by the Fraunhofer ('Far-Field') Approximation.

reportActive / Technical Report | Accession Number: ADA186399 | Open PDF

Abstract:

The overestimation of power density by the Fraunhofer far-field approximation to the more exact Fresnel near-field diffraction integral is determined as a function of Fresnel number at arbitrary on-axis field points for rectangular and circular aperture illuminations of uniform amplitude and phase. For square and circular apertures, the overestimation is 2.8 percent and 1.3 percent, respectively, at a Fresnel number of 18 corresponding to the far field boundary distance D-sq lambda and 518 percent and 147 percent, respectively, at a Fresnel number of 1. Keywords Antenna aperture Aperture distribution of uniform intensity and phase circular aperture Constructive interference Destructive interference Diffraction Fresnel kirchhoff integral Fresnel number Optical aperture Rectangular aperture.

Author(s):
Weiner, Melvin M.
Author Organization(s):
MITRE CORP BEDFORD MA
Descriptive Note:
Final rept.,
Supplementary Note:
DOI: 10.21236/ADA186399
Pagination:
0025

Security Markings

DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
M87-37, ESD-TR-87-234
Contract/Grant Number(s):
F19628-86-C-0001
Project Number(s):
414J
Monitor Series:
TR-87-234
 Subject Terms
Communities of Interest:
Energy and Power Technologies
Descriptor(s):
*DIFFRACTION, *ELECTROMAGNETIC WAVE PROPAGATION, *ANTENNA APERTURES, AXES, DENSITY, DESTRUCTION, DISTRIBUTION, FRESNEL INTEGRALS, INTENSITY, INTERFERENCE, POWER, FAR FIELD, ESTIMATES, SHAPE, CIRCLES
Field(s)/Group(s):
Electricity and Magnetism
Keyword(s):
*Fraunhofer Approximation, Squares
Report Date:
1987 Apr 01