Far-Field Prediction using Only Magnetic Near-Field Scanning for EMI Test


Far-field prediction for electromagnetic interference (EMI) testing is achieved using only magnetic near-field on a Huygens's surface. The electrical field on the Huygens's surface is calculated from the magnetic near-field using the finite element method (FEM). Two examples are used to verify the proposed method. The first example uses the field radiated by an infinitesimal electric dipole. The calculated results are compared with the analytical solution. In the second example, the calculated results are compared with full-wave simulation results for the radiation of a print circuit board (PCB). The validity of this method when the near-field is high-impedance field is verified as well. Sensitivity of the far field to noise in both magnitude and phase in the near-field data is also investigated. The results indicate that the proposed method is very robust to the random variation of both. The effect of using only four sides of the Huygens's box is investigated as well, revealing that, in some instances, the incomplete Huygens's box can be used to predict the far field well. The proposed method is validated using near-field measurement data taken from a sleeve dipole antenna. The error for the maximum far-field value is in only 1.3 dB.


Electrical and Computer Engineering

Research Center/Lab(s)

Center for High Performance Computing Research

Second Research Center/Lab

Electromagnetic Compatibility (EMC) Laboratory

Keywords and Phrases

Dipole antennas; Electromagnetic pulse; Electromagnetic wave interference; Forecasting; Magnetic fields; Signal interference; Electrical field; Equivalence theorem; Full-wave simulations; Near-field measurement; Near-field scanning; Near-field-far-field transformations; Print circuit boards; Random variation; Finite element method

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


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© 2014 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Dec 2014