Advanced Electromagnetics (E-Journal)
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299 research outputs found
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General Lossy External Cloak with New Structures
No full textIn this article we consider loss for all parts of external cloaks that are achieved by the different transformation functions. Each cloak has a different threshold for loss. We compare the simulation result with each other to find the best function for external cloaking
Finite Difference Time-Domain Modelling of Metamaterials: GPU Implementation of Cylindrical Cloak
No full textFinite difference time-domain (FDTD) technique can be used to model metamaterials by treating them as dispersive material. Drude or Lorentz model can be incorporated into the standard FDTD algorithm for modelling negative permittivity and permeability. FDTD algorithm is readily parallelisable and can take advantage of GPU acceleration to achieve speed-ups of 5x-50x depending on hardware setup. Metamaterial scattering problems are implemented using dispersive FDTD technique on GPU resulting in performance gain of 10x-15x compared to conventional CPU implementation
Electric and Magnetic Coulomb Potentials in the Deuteron
No full textAfter one century of nuclear physics, the underlying fun- damental laws of nuclear physics are still missing. Bohr had found a formula for the H atom and another for the H2 molecule but no equivalent formula exists for the deuteron 2H. The only known Coulomb interaction in a nucleus by the mainstream nuclear physics is the long range repulsion between protons, forgetting that the neutron contains elec- tric charges with no net charge. The neutron is attracted by the proton in a way discovered two millenaries ago by the Greeks. This attraction is equilibrated by the repulsion between the opposite magnetic moments of the proton and of the neutron in the deuteron. The bare application of ge- ometry together with electric and magnetic Coulomb’s in- teractions accounts for the binding energy of the deuteron, without fitting, with only 4 per cent discrepancy, proving the electromagnetic nature of the nuclear energy. 
Beam Steering at Higher Photonic Bands and Design of a Directional Cloak Formed by Photonic Crystals
No full textBeam steering due to anomalous dispersion at higher photonic bands in dielectric photonic crystal is reported in this work. Based on this concept, directional cloak is designed that conceals a larger dimensional scattering object against the normal incident, linearly polarizedelectromagnetic waves
Electromagnetic field in matter. Surface enhanced Raman scattering
No full textThe polarization and magnetization degrees of freedom are included in the general treatment of the electromagnetic field in matter, and their governing equations are given. Particular cases of solutions are discussed for polarizable, non-magnetic matter, including quasi-static fields, surface plasmons, propagation, zero-point fluctuations of the eigenmodes, especially for a semi-infinite homogeneous body (half-space). The van der Waals London-Casimir force acting between a neutral nano-particle and a half-space is computed and the response of this electromagnetically coupled system to an external field is given, with relevance for the surface enhanced Raman scattering
Resonant Frequency of Tunable Microstrip Ring Antenna Printed on Isotropic or Uniaxially Anisotropic Substrate
No full textIn this study, the resonant frequency of annular ring microstrip resonator with uniaxial anisotropic substrate and air gap layer is analyzed. The cavity model for simple ring microstrip antenna is extended with some modifications for the tunable geometry taking into account the anisotropy in the layer. The theoretical resonant frequency results are in very good agreement with the experimental results reported elsewhere. The air gap tuning effect on the resonant characteristics is also investigated for fundamental and higher order modes
Electromagnetic Absorbers based on High-Impedance Surfaces: From ultra-narrowband to ultra-wideband absorption
No full textDifferent electrically-thin absorbing designs based on High-Impedance Surfaces (HIS) are presented and classified on the basis of the nature of loss. HIS structures allow achieving absorption by exploiting either dielectric or ohmic (resistive) losses. The former ultra-narrowband absorption phenomenon can be obtained by employing dielectric losses of commercial substrates. The resonant structure, often referred to as Perfect Metamaterial Absorber, usually comprises a metallic frequency selective surfaces located above a ultra-thin grounded dielectric substrate. The metamaterial absorber is also angularly stable because of its reduced thickness. Alternatively, if a loss component is introduced in the frequency selective surface located in front of the grounded dielectric substrate both narrowband and wideband absorbing structures can be designed
Difficulties in teaching electromagnetism: an eight year experience at Pierre and Marie Curie University
No full textWe will begin by outlining the details of how electromagnetics are taught in the electrical engineering program offered at Pierre and Marie Curie University (a French example) from the undergraduate to the Masters degree levels. We will also discuss how our methods are and should be adapted to teach waves propagation without discouraging students
Application of Near-Field Emission Processing for Microwave Circuits under Ultra-Short Duration Perturbations
No full textThis paper is dealing with a time-frequency modeling method of electromagnetic (EM) near-field (NF) radiated by electronic devices excited by transient pulse signals. The model developed enables to calculate the EM NF maps at different distances from the given device and also the synthesis of radiation sources enabling to reproduce the field maps. The method proposed is based on the ultra wide band (UWB) frequency model of EM NF maps. The number of EM NF maps can be reduced by considering an innovative algorithm in order to establish simply the dipole model. Then, the transient model can be realized by considering the convolution between the transient excitation signals and the dipole-array model. The method proposed was validated by a standard 3D EM tool with a planar microstrip device excited by microwave signal modulating 1.25-GHz-carrier with 0.5-GHz-bandwidth. As expected, good correlation is found between results from simulation and the investigated modelling method. The method introduced in this paper is particularly useful for the investigation of time-domain emissions for EMC applications by considering transient EM interferences (EMIs)
Simulation of Plasmonics Nanodevices with Coupled Maxwell and Schrödinger Equations using the FDTD Method
No full textMaxwell and Schrödinger equations are coupled to incorporate quantum effects for the simulation of plasmonics nanodevices. Maxwell equations with Lorentz-Drude (LD) dispersive model are applied to large size plasmonics components, whereas coupled Maxwell and Schrödinger equations are applied to components where quantum effects are needed. The finite difference time domain method (FDTD) is applied to simulate these coupled equations