Article

An Effective Near-Field-Far-Field Transformation Technique for Elongated Antennas Using a Fast Helicoidal Scan

IEEE Antennas and Propagation Magazine (Impact Factor: 1.32). 09/2009; 51(4):134 - 141. DOI: 10.1109/MAP.2009.5338700
Source: IEEE Xplore

ABSTRACT

An experimental validation of a new near-field-far-field transformation technique with helicoidal scanning, tailored for elongated antennas, is provided in this paper. Such a transformation is based on non-redundant sampling representations of the electromagnetic fields. It makes use of a flexible source modeling, which allows one to very well fit many of these kinds of antennas by properly setting the geometric parameters. By employing such modeling instead of spherical modeling, it is possible to remarkably reduce the error related to the truncation of the scanning zone, since measurement cylinders with a diameter smaller than the antenna's height can be used. A comparison of the reconstructions recovered from the non-redundant measurements on the helix with those obtained from data directly measured on the classical cylindrical grid assesses the validity of this innovative scanning technique.

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    ABSTRACT: An effective technique to compensate the positioning errors in a near-field - far-field (NF-FF) transformation with helicoidal scanning for long antennas is presented and experi- mentally validated. It relies on a nonredundant sampling repre- sentation of the probe voltage obtained by considering the an- tenna as enclosed in a cylinder ended in two half-spheres and employs an iterative scheme to reconstruct the helicoidal NF data at the points fixed by the representation from the acquired ir- regularly spaced ones. Once the helicoidal data have been re- trieved, those needed by a standard NF-FF transformation with cylindrical scan are efficiently evaluated by using an optimal sampling interpolation algorithm. The comparison of the FF pat- terns reconstructed from the irregularly spaced measurements with those obtained from the data directly acquired on the classi- cal cylindrical grid assesses the effectiveness of the approach. I. INTRODUCTION
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    ABSTRACT: An effective procedure is developed in this paper to compensate the probe positioning errors when using a near-field to far-field transformation technique with helicoidal scanning for long antennas. It is based on a prolate ellipsoidal modelling of the antenna under test and makes use of an iterative scheme to retrieve the uniformly distributed helicoidal near-field data from the irregularly spaced acquired ones. Once these data have been recovered, those required to perform a standard near-field-far-field transformation with cylindrical scanning are efficiently determined via an optimal sampling interpolation algorithm. Some numerical tests are reported to assess the accuracy of the approach and its robustness with respect to random errors affecting the data. At last, the validity of the developed technique is further confirmed by the experimental tests performed at the Antenna Characterization Lab of the University of Salerno.
    Full-text · Article · Jan 2011 · Progress In Electromagnetics Research C
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    [Show abstract] [Hide abstract]
    ABSTRACT: An effective procedure is developed in this paper to compensate the probe positioning errors when using a near-field to far-field transformation technique with helicoidal scanning for long antennas. It is based on a prolate ellipsoidal modelling of the antenna under test and makes use of an iterative scheme to retrieve the uniformly distributed helicoidal near-field data from the irregularly spaced acquired ones. Once these data have been recovered, those required to perform a standard near-field-far-field transformation with cylindrical scanning are efficiently determined via an optimal sampling interpolation algorithm. Some numerical tests are reported to assess the accuracy of the approach and its robustness with respect to random errors affecting the data. At last, the validity of the developed technique is further confirmed by the experimental tests performed at the Antenna Characterization Lab of the University of Salerno.
    Preview · Article · Jan 2011 · Progress In Electromagnetics Research C
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