This paper proposes an autonomous coil alignment system (ACAS) for electric vehicles (EVs) with dynamic wireless charging (DWC) to mitigate the reduction in received power caused by lateral misalignment between the source and load coils. The key component of the ACAS is a novel sensor coil design, which can detect the load coil’s left or right position relative to the source coil by observing the change in voltage phase. This allows the lateral misalignment to be estimated through the wireless power transfer (WPT) system alone, which is a novel tracking method for vehicular applications. Once misalignment is detected, the vehicle’s lateral position is self-adjusted by an autonomous steering function. The feasibility of the overall operation of the ACAS was verified through simulation and experiments. In addition, an analysis based on experimental results was conducted, demonstrating that 26% more energy can be transferred during DWC with the ACAS, just by keeping the vehicle’s load coil aligned with the source coil.

Recent smartphones increasingly employ a metal frame for a sophisticated design. However, the metal frame becomes a good coupling path for electromagnetic (EM) noise within smartphones and increases noise coupling to radio-frequency antennas located at the top and bottom sides of the smartphones. This paper proposes two novel metal frame structures with ferrite absorbing sheets or electromagnetic band gap patterns to reduce the coupling of EM noise to the antenna. Using a fabricated test board, the effects of the proposed metal frames on noise coupling suppression are experimentally validated.

This paper presents a simple equivalent circuit model for estimating shielding performance of thin and flexible magnetic sheets or films, which are commonly used in modern mobile devices, such as smartphones. The proposed equivalent circuit model can accurately and effectively represent the measurement setup using a microstrip line and a loop probe that are typically employed to evaluate a near-field shielding effectiveness (SE) of commercial magnetic absorbing sheets or films. The calculated SEs of magnetic sheets using the proposed equivalent circuit model are validated by 3-D electromagnetic simulation and experiment, and show good agreement with measurement results in the frequency range up to 0.5 GHz.

In this article, analytic models are proposed for electromagnetic shielding analysis of planar materials using the ASTM D4935 standard fixture typically employed to measure far-field shielding effectiveness (SE). The fixture with an inserted planar material is divided into two coaxial line sections and one material section that are modeled as lossless and lossy transmission lines (TLs), respectively. Using the ABCD parameters of TLs, the far-field SEs of planar materials are analytically derived and calculated. In order to analyze the case where the conductive materials are coated on insulating substrates, contact impedances are considered at the inner and outer conductors of the flanged coaxial fixture. The proposed high-frequency model can accurately predict the absorption loss especially in the high-frequency where the skin depth of the material becomes smaller than its thickness. Low-frequency and lumped models are also derived by approximation of the high-frequency model. In addition, correction factors are introduced to remove the SE error in the low-frequency range due to the attached insulating substrates of the conducting materials. For verification, the proposed models are compared with the theoretical plane-wave SE and the measurement results presented in other literatures. They show a good agreement with each other. Lastly, an influence of the errors in the thicknesses and electrical parameters of actual materials on the analytic SE models is analyzed.

In this paper, an analytical solution is presented for magnetic shielding analysis of a slit on a conducting plate coated with a ferrite sheet. The Fourier transform and the mode matching technique are employed to obtain the analytical solution for magnetic vector potential. Magnetic shielding effectiveness is investigated in terms of the geometrical parameters of a slit on a conducting plate and a ferrite sheet. The proposed method is numerically validated by a commercial finite element solver with good agreement. In addition, the proposed analytical solution is in a rapidly converging series so that it is more efficient than other numerical techniques.

This article proposes an analytical formulation to calculate the magnetic near-field shielding effectiveness (SE) of a metal plate with multiple long slots in the low frequency range below 10 MHz. Mutual inductances of two rectangular loop antennas in the presence and absence of the metal plate with slots are analytically derived. Then, the magnetic SE is obtained by the ratio of two analytic mutual inductances. In addition, an analytical SE formulation based on the transmission line model is used to consider the diffusion effect caused by a low conductivity of the metal plate. The total magnetic SE is finally determined by choosing the minimum SE between two analytic results due to the slot and diffusion effects. For validation, the results obtained by the proposed method are compared with the numerical results of full-wave simulation, and good agreement is achieved.