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In high voltage transmission lines, shield wires are periodically grounded and can be periodically sectionalized for several purposes. These two practices have important effects on multiconductor transmission lines, since both affect the wave propagation along the line. In this work, the attention is focused on the frequency behavior of the characteristic impedance. Moreover, the effect of wires transposition...
The performance of electromagnetically thin planar shields are investigated in the time domain considering near field sources in order to extract the relevant features of reference configurations. The analysis is performed numerically and the influence of shield constitutive parameters and of the source distance on the relevant time-domain shielding parameters is also presented.
The shielding effectiveness of thin planar shields against magnetic field is investigated in the time domain. The analysis is performed considering a vertical magnetic dipole as the source and a classical twelve inches diameter loop as receiving antenna. The computations are performed through a recently proposed analytical solution. The relevant features of classical configurations are extracted and...
The continuity of shield wires is often broken for losses reduction purposes in high voltage transmission lines. The accurate simulation of the effects of this practice on power line communications in multiconductor transmission lines is performed in the time domain by means of a finite-difference method. Losses in wires and ground are accounted for by means of transient per unit length parameters...
Different corona models are investigated with reference to the propagation along lossy overhead multiconductor transmission lines of overvoltages due to direct lightning strokes. A nonlinear dynamic capacitance is introduced to simulate the nonlinear behavior of the q-v hysteretic loop and account for the losses associated with its area. For comparison, an equivalent circuit has been introduced to...
Propagation and attenuation properties of modes supported by graphene nano-ribbons placed on top of a grounded dielectric substrate are investigated by means of a spectral-domain Method-of-Moments approach together with a dyadic description of the graphene conductivity obtained based on semiclassical and quantum-mechanical arguments. Such a description takes into account the possible presence of static...
New emerging threats, like intentional EMI, new possibilities offered by material technologies, a renewed awareness of theoretical subtleties have driven several advancements and researches in electromagnetic shielding aimed not only at improving the protection levels as commonly intended but also at achieving deeper insights into the various and fundamental issues involved in shielding problems.
A novel Frequency Selective Surface (FSS) is proposed for the design of polarization-insensitive metamaterial absorbers that operate around 1 GHz, where the first resonances of small commercial enclosures take place. The novel FSS is based on the simplification of an alternative Roman maze. It shows a strong sub-wavelength response and is promising for the design of compact planar absorbers with excellent...
ZnO is receiving a considerable attention for the development of novel cost-effective one-dimensional nanostructures with outstanding functional properties for applications in electronics and energy. We propose a fully-coupled thermo-mechanical-electric scheme to study the current-voltage characteristic of piezoelectric ZnO NWs under a purely vertical compressive/tensile strain. Our results confirm...
Prediction of the potential threats due to direct lightning strokes of sensitive targets, e.g., overhead power-line towers, substations or buildings, requires accurate modeling of the transient impedance of grounding systems. When large-scale simulations are needed, detailed and computationally intensive models are hardly viable, although they usually offer great accuracies. In this work we investigate...
The fundamental modes supported by a pair of identical graphene nanoribbons in the presence of a ground plane are analyzed. Dispersion, attenuation, and characteristic impedance of each mode are determined and an equivalent circuit is extracted. An efficient full-wave approach is adopted, based on a Method-of-Moments discretization of the relevant electric-field integral equation in which the graphene...
Dispersion, attenuation and characteristic impedance of the fundamental modes supported by a pair of identical graphene nanoribbons in free space are studied. An efficient full-wave approach is adopted, based on a method-of-moments discretization of the relevant electric-field integral equation in which the graphene is modeled through a simple local conductivity. A spatial-domain formulation is adopted...
A computer-aided methodology for designing multiport broadband impedance matching circuits (BIM) to be connected at powerline communication (PLC) networks is presented in order to provide gain equalization and mitigation of the effects of low-impedance loads among transmitter and receivers in a wide frequency range. The design is achieved in successive steps by means of the Vector Fitting method,...
The excitation of a periodic structure composed of two- or three-dimensional metallic scatterers by a finite dipole source is studied through the application of the Array Scanning Method. The difficulties in the numerical implementation are discussed in details, providing general guidelines and suggesting a useful preprocessing procedure to determine the number of quadrature points needed in the involved...
The objective of this paper is to investigate the use of periodic artificial materials for shielding high-frequency high-impedance near fields produced by electric dipoles. The problem is handled numerically by applying the Array Scanning Method that reduces the problem of an aperiodic source close to a periodic screen to a superposition of phased-dipole-array problems (where the array periods are...
Powerlines can provide an economical medium for high-speed communications; however, the low-voltage electrical network is an unfriendly environment with interferences, noise, attenuation, and multi-path reflections. This paper presents a reliable multi-step procedure for designing an optimal broadband impedance-matching circuit providing gain equalization and mitigation of the effects of low-impedance...
The evaluation of the shielding effectiveness of metallic enclosures with apertures containing metallic objects and excited by arbitrary sources is the main topic of this work. The shielding effectiveness is computed through an integral formulation based on the Method of Moments which makes use of a fast computation of the enclosure Green functions. Absorbing artificial materials are also designed...
Performance of artificial planar screens composed of small magnetic elements are investigated through equivalent circuit models and a full-wave approach involving a periodic method-of-moments formulation. The conventional split-ring resonator screen is first studied and next the geometry of the single inclusion is modified in order to reduce the operating frequency of the screen. It is shown how the...
The low-voltage powerline communication (PLC) field constitutes today a hot open research area. Powerlines, that often already exist to support energy distribution, can provide an economical broadband medium for high-speed reliable communication traffic, not only for equipment monitoring, protection, and control purposes, but especially today for supporting the smart home technology. However, despite...
A planar screen made of a periodic array of small resonant particles showing a strong magnetic resonance is studied in detail. Two types of inclusions are considered: the double split-ring resonator (SRR) and the spiral resonator (SR). The homogenized screen is shown to behave as a homogeneous slab with an effective magnetic permeability having large positive or negative values around the magnetic...
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