Auxiliary sources for the near-to-far-field transformation of magnetic near-field data

A direct near-field-far-field transformation with helicoidal scanning is developed. It is based on the nonredundant sampling representation of electromagnetic fields and uses a spherical antenna modelling to determine the number of helix turns. Moreover, the number of voltage samples on each of them is fixed by the maximum transverse dimension of the antenna, both to simplify the mechanical scanning and to reduce the computational effort. This technique allows the evaluation of the antenna far field directly from a minimum set of near-field data without interpolating them. Although the number of near-field data employed by the developed technique is slightly increased with respect to that required by rigorously applying the nonredundant sampling representation on the helix, it is still remarkably smaller than that needed by the standard near-field-far-field transformation with cylindrical scanning. The effectiveness of the technique is assessed by numerical and experimental results.

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A far-field transformation from phaseless near-field data on helicoidal geometry

IEEE Antennas and Propagation Society Symposium, 2004. ◽

10.1109/aps.2004.1329768 ◽

2004 ◽

Author(s):

S. Costanzo ◽

G. Di Massa

Keyword(s):

Field Data ◽

Near Field ◽

Far Field ◽

Field Transformation

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Phaseless spherical near-field antenna measurements for low and medium gain antennas

Advances in Radio Science ◽

10.5194/ars-8-43-2010 ◽

2010 ◽

Vol 8 ◽

pp. 43-48 ◽

Cited By ~ 19

Author(s):

C. H. Schmidt ◽

S. F. Razavi ◽

T. F. Eibert ◽

Y. Rahmat-Samii

Keyword(s):

Special Interest ◽

Field Data ◽

Measurement Accuracy ◽

Near Field ◽

Far Field ◽

Radiation Patterns ◽

Phase Measurements ◽

Modal Expansion ◽

Field Transformation ◽

Phase Data

Abstract. The characterisation of antenna radiation patterns by measurements in the near-field and a following near-field far-field transformation require accurate amplitude and phase data. Especially at higher frequencies phase measurements are demanding in terms of instrumentation and measurement accuracy. Phaseless techniques which require amplitude only data on one or more measurement surfaces are therefore of special interest. In this paper a phaseless spherical algorithm based on spherical modal expansion is presented. The algorithm works with amplitude only near-field data measured on two spheres of different radii and is therefore not restricted to certain types of antennas as for planar measurements for example. Simulated as well as measured results of low and medium gain antennas are shown.

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An Efficient Transformation Technique for the Direct Recovering of the Antenna Far-Field Pattern from Near-Field Measurements Collected along a Helix

The Open Electrical & Electronic Engineering Journal ◽

10.2174/1874129001307010021 ◽

2013 ◽

Vol 7 (1) ◽

pp. 21-30 ◽

Cited By ~ 1

Author(s):

F. D'Agostino ◽

F. Ferrara ◽

C. Gennarelli ◽

R. Guerriero ◽

M. Migliozzi

Keyword(s):

Electromagnetic Fields ◽

Field Data ◽

Near Field ◽

Field Measurements ◽

Field Pattern ◽

Far Field ◽

Transformation Technique ◽

Computational Burden ◽

Field Transformation ◽

Far Field Pattern

A near-field to far-field transformation technique with helicoidal scanning for elongated antennas, which allows the evaluation of the antenna far-field pattern in any cut plane directly from a nonredundant number of near-field data without interpolating them, is developed in this paper. It is based on the nonredundant sampling representations of electromagnetic fields and employs a flexible source modelling suitable for long antennas to determine the number of helix turns. The number of near-field measurements on each turn is on the contrary dictated by the minimum cylinder rule, as in the classical cylindrical scanning, in order to reduce the computational burden and to simplify the scanning from the mechanical viewpoint. Some numerical and experimental results assessing the effectiveness of the proposed technique are reported.

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Near-Field/Far-Field Transformation with Helicoidal Scanning from Irregularly Spaced Data

International Journal of Antennas and Propagation ◽

10.1155/2010/859396 ◽

2010 ◽

Vol 2010 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Francesco D'Agostino ◽

Flaminio Ferrara ◽

Claudio Gennarelli ◽

Rocco Guerriero ◽

Massimo Migliozzi

Keyword(s):

Field Data ◽

Iterative Scheme ◽

Near Field ◽

Optimal Sampling ◽

Far Field ◽

Interpolation Algorithm ◽

Random Errors ◽

Numerical Tests ◽

Positioning Errors ◽

Field Transformation

A fast and accurate technique for the compensation of the probe positioning errors in the near-field/far-field transformation with helicoidal scanning is proposed in this paper. It relies on a nonredundant sampling representation using a spherical modelling of the antenna under test and employs an iterative scheme to evaluate the near-field data at the points fixed by the helicoidal nonredundant representation from the acquired irregularly distributed ones. Once these helicoidal data have been recovered, those required by a classical cylindrical near-field/far-field transformation are efficiently determined by using an optimal sampling interpolation algorithm. Some numerical tests assessing the effectiveness of the proposed approach and its stability with respect to random errors affecting the near-field data are shown.

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