Summary
International Symposium on Electromagnetic Compatibility
2014
Session Number:15A2-A
Session:
Number:15A2-A3
The Electric Field Response of the Van Veen Loop
James McLean, Koji Takizawa, Armando Medina, Robert Sutton,
pp.-
Publication Date:2014/05/12
Online ISSN:2188-5079
Summary:
The Van Veen Loop, Large Loop Antenna (LLA), or Loop Antenna System (LAS) provides rapid determination of the net magnetic dipole moment of compact devices, especially in the frequency range of 9 kHz to 30 MHz with minimal post processing of measured data. The symmetric shielded loop structure inherently rejects electric field excitation to a large extent. Here, the response of the Van Veen Loop to an electric dipole source is considered. The electric field response is much stronger near the upper end of the operating frequency range for several reasons. One reason is the common-mode response of the requisite current transformer which, in turn, is due to the unavoidable inter-winding capacitance in the device. This is true even when the current transformer employs an electrostatic shield between the primary and secondary. Another important reason is the frequency response of the complex internal network of the LLA. Finally, the electric field response of the external structure, the ``antenna'' itself, increases monotonically with frequency below the fundamental series resonance. The electric field response of the external structure is strongly affected by the presence of dielectric supporting material for the LLA, while the magnetic field response is only slightly perturbed. In particular, the fundamental series resonance of the structure is reduced to the point that it is near the 30 MHz upper frequency limit of the operating frequency range. The impetus for this work is the application of the LLA to the characterization of Inductive Power Transfer (IPT) systems. It has been shown that such IPT systems exhibit, in addition to an intense magnetic dipole moment, an intense electric dipole moment. This is due primarily to the turn-to-turn voltage drop in inductive couplers. The question which we seek to answer is, given a non-ideal LLA and such a DUT with a strong electric dipole moment, how much common-mode rejection must the current transformer have in order to provide accurate assessment of the magnetic dipole moment of the DUT?