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Circular scanning and equivalent magnetic currents for main plane near‐field to far‐field transformation
Author(s) -
LasHeras F.,
Galocha B.,
Besada J. L.
Publication year - 2002
Publication title -
international journal of numerical modelling: electronic networks, devices and fields
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.249
H-Index - 30
eISSN - 1099-1204
pISSN - 0894-3370
DOI - 10.1002/jnm.455
Subject(s) - near and far field , radiation pattern , antenna (radio) , field (mathematics) , transformation (genetics) , plane (geometry) , optics , physics , magnetic field , polar coordinate system , geometry , polar , mathematical analysis , mathematics , computer science , telecommunications , biochemistry , chemistry , quantum mechanics , astronomy , pure mathematics , gene
A method to obtain a main plane far‐field radiation pattern of an antenna under test (AUT) from the correspondent main plane near‐field pattern in a circular scanning is presented. The method is based on the reconstruction of a set of magnetic equivalent currents radiating in free space that represents the AUT. The method can be applied to the measurement of antennas with a linear distribution or with a two‐dimensional distribution under certain considerations that allow to establish integral equations relating field components and one‐dimensional current components. A Levenberg–Marquardt algorithm is used to minimize the least squares error between the fields radiated by the equivalent currents and the measured field. The far field at every aspect angle is obtained from the calculated sources. Calculations of co‐polar and cross‐polar far‐field pattern from measured near‐field data of array antennas have been carried out to compare the proposed method with a full spherical scanning followed by a spherical wave expansion method. Copyright © 2002 John Wiley & Sons, Ltd.