Ricerc@Sapienza

The magnetic shielding effectiveness of a planar metallic screen of infinite extent against a circular loop field source is analytically evaluated in a new closed-form formula under the thin sheet and small-loop approximations. The results obtained with the proposed formulation are compared with the exact ones derived numerically and with those obtained through classical approximate formulations.

A novel design of active coil shielding is proposed to reduce the magnetic field generated by the currents flowing into the coils of a wireless power transfer (WPT) system for charging the batteries of an electric vehicle (EV). The main idea is to divide the traditional active loop used to shield a source in two separate shielding coils so as not to adversely affect the WPT performance.

The shielding technique by active coils is proposed to mitigate the magnetic field produced by a dynamic wireless power transfer (WPT) system for wireless recharging the batteries of in motion electrical vehicles (EVs). Active planar coils mounted in an electrified road with multiple-pads architecture are proposed. The active coils are adequately powered so that the field in surrounding of the electrified road is compliant with reference levels (RLs) of ICNIRP 2010 guideline. The influence of the active shielding system on the performance of the WPT system is also investigated.

This study deals with the optimization of a shielding structure composed by multiple active coils for mitigating the magnetic field in an automotive wireless power transfer (WPT) system at 85 kHz. Each active coil is independently powered and the most suitable excitation is obtained by an optimization procedure based on the Gradient Descent algorithm. The proposed procedure is described and applied to shield the magnetic field beside an electric vehicle (EV) equipped with SAE standard coils, during wireless charging.

A novel design of active coils is proposed to reduce the magnetic field generated by the currents flowing into the coils of a wireless power transfer (WPT) system for recharging the batteries of an electric vehicle (EV). The main idea is to split the traditional active loop, in two separate shielding coils. They have semi-annular shape and are placed on the ground pad around the WPT primary coil. The geometry and excitation of the active coils are varied to minimize the magnetic field beside the active coils without degrading the WPT electrical performance.

The shielding technique by active coils is proposed to mitigate the magnetic field produced by a wireless power transfer (WPT) system based on near field coupling. General guidelines are provided for the active shielding design to shield the source for emission reduction or to shield the victim for immunity enhancement. Then, a method is proposed to identify the suitable excitation of the active coils. The proposed method permits the mitigation of the magnetic field in a specific point or of the induced effects in a loop area.

An active coil system is proposed to shield the magnetic field produced by a dynamic wireless power transfer (WPT) system used to power electric vehicles (EVs) in motion. The considered dynamic WPT is based on an electrified road with many short-track pads. A sophisticated mathematical procedure is developed to optimize the design of the active coils configuration and their excitation.

The possibility to generate a nondiffracting Bessel beam by means of a fast backward spatial harmonic supported by an annular metal-strip grating placed on a grounded dielectric slab is demonstrated. The focusing capabilities of the relevant leaky-wave aperture field are investigated in conjunction with the dispersive analysis of the considered structure. Full-wave simulations of a prototype are developed using a commercial code. The proposed design represents an attractive simple and low-cost solution potentially able to generate an arbitrary-order nondiffracting beam.

In this contribution, we describe the design and the radiation features of a dual-mode operation low-profile, low-cost, wideband antenna. The structure is made by an annular, 2-D radially periodic, leaky-wave antenna enabling the generation of both high-gain beams in the far-field and of nondiffracting waves within the near-field radiative region. This is obtained through the generation of a fast backward spatial harmonic supported by a metal-strip grating placed on a grounded dielectric slab.

The generation of higher-order cylindrical leaky waves (HOCLWs) by means of canonical electric or magnetic ring sources was discussed in Part I, where radiation formulas for such waves were also presented. In the second part of this sequence, the practical excitation of HOCLWs in a Fabry–Perot cavity antenna is discussed considering the use of ring sources in a discrete form, i.e., circular phased arrays of vertical electric or horizontal magnetic dipoles.