An Automatic Near-field Characterization System with Multipolar Expansion Approach
Résumé
The importance of the radiated equivalent sources characterization andElectromagnetic Compatibility studies has been emphasized in the presentliterature. It mentions the methodology based on the multipolar expansion inspherical harmonics of the near-field sources. Details of this methodology andof the prototypes suitable for determining components of the multipolarexpansion are shown, for instance, in (Vincent, Benjamin, et al. "Loopantennas for near-field multipolar-expansion identification: first experimentalvalidations." Instrumentation and Measurement, IEEE Transactions on 59.12(2010): 3086-3092.), and T. Q. V. Hoang, A. Bréard, and C. Vollaire, “NearMagnetic Field Coupling Prediction Using Equivalent Spherical HarmonicSources,” IEEE Trans. on EMC, Vol. 56, n°6, pp. 1457-1465, 2014.).Nevertheless, these prototypes requires that either the device under test or theloop sensors be constantly positioned between all the measurements, to get theproper components necessary to represent accurately complex radiatedsources, thus resulting in a time-demanding approach.In order to minimize the aforementioned constraints, an automatic system isproposed, in which the positioning feedback is done by computer vision andthe movement is provided by stepper motors, and nonmagnetic pulleys,carefully located and operated in order to not interfere in the fieldmeasurements. To improve the mechanical precision, the main mechanicalcomponents or parts of this system were carried out using CNC equipment.The validation was based in previous results obtained by the authors.Although, the spherical harmonics are used so far, the proposed system alsoallows implementing the equivalent cylindrical ones, being considered as partof future work. Thus, higher degrees of precision will be allowed, since higherorder and degrees of the desired component of the multipolar expansion can beobtained by this system.