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Important statistical variations are likely to appear in the propagation of surface plasmon polariton waves atop the surface of graphene sheets, degrading the expected performance of real-life THz applications. This paper aims to introduce an efficient numerical algorithm that is able to accurately and rapidly predict the influence of material-based uncertainties for diverse graphene configurations.

Initially, the surface conductivity of graphene is described at the far infrared spectrum and the uncertainties of its main parameters, namely, the chemical potential and the relaxation time, on the propagation properties of the surface waves are investigated, unveiling a considerable impact. Furthermore, the demanding two-dimensional material is numerically modeled as a surface boundary through a frequency-dependent finite-difference time-domain scheme, while a robust stochastic realization is accordingly developed.

The mean value and standard deviation of the propagating surface waves are extracted through a single-pass simulation in contrast to the laborious Monte Carlo technique, proving the accomplished high efficiency. Moreover, numerical results, including graphene’s surface current density and electric field distribution, indicate the notable precision, stability and convergence of the new graphene-based stochastic time-domain method in terms of the mean value and the order of magnitude of the standard deviation.

The combined uncertainties of the main parameters in graphene layers are modeled through a high-performance stochastic numerical algorithm, based on the finite-difference time-domain method. The significant accuracy of the numerical results, compared to the cumbersome Monte Carlo analysis, renders the featured technique a flexible computational tool that is able to enhance the design of graphene THz devices due to the uncertainty prediction.

To outline different versions of a novel method for accurate and efficient determining the dielectric properties of arbitrarily shaped materials.

Complex permittivity is found using an artificial neural network procedure designed to control a 3D FDTD computation of S‐parameters and to process their measurements. Network architectures are based on multilayer perceptron and radial basis function nets. The one‐port solution deals with the simulated and measured frequency responses of the reflection coefficient while the two‐port approach exploits the real and imaginary parts of the reflection and transmission coefficients at the frequency of interest.

High accuracy of permittivity reconstruction is demonstrated by numerical and experimental testing for dielectric samples of different configuration.

Dielectric constant and the loss factor of the studied material should be within the ranges of corresponding parameters associated with the database used for the network training. The computer model must be highly adequate to the employed experimental fixture.

The method is cavity‐independent and applicable to the sample/fixture of arbitrary configuration provided that the geometry is adequately represented in the model. The two‐port version is capable of handling frequency‐dependent media parameters. For materials which can take some predefined form computational cost of the method is very insignificant.

A full‐wave 3D FDTD modeling tool and the controlling neural network procedure involved in the proposed approach allow for much flexibility in practical implementation of the method.

The paper presents the band gap computation in one‐ and two‐dimensional photonic crystals built up from porous silicon. The frequency dispersion of the dielectric materials is taken into account.

The behavior of the light in a photonic crystal can be well described by the Maxwell equations. The finite difference time domain (FDTD) method is applied to determine the band structure. The frequency dependence of the dielectric constant is taken into account by a sum of second‐order Lorenz poles. The material parameters are determined applying a conjugate gradient‐based minimization procedure. Passing a light pulse of Gaussian distribution through the photonic crystal and analyzing the transmitted wave can explore the photonic bands.

The realized simulations and visualizations can lead to a much better understanding of the behavior of electromagnetic waves in dispersive photonic crystals, and can make possible to set up experimental conditions properly. The obtained results show again that silicon and porous silicon can be used for the fabrication of photonic crystals.

Due to the high computational requirements of the three‐dimensional case we plan to work out a parallel version of the presented FDTD algorithm.

This paper presents a simple way to take into account the frequency dispersion in the simulation of photonic crystals with the FDTD method.

The narrow‐wall inclined‐slot coupling between rectangular waveguides from an H‐plane T‐junction, is numerically analysed, for the first time, via a 3D generalised locally conformed FDTD technique. The structure is excited by a combined pulsed modulated TE_mn mode scheme which enables the imposition of higher‐order ABCs or advanced PMLs very close to the slot, thus achieving significant reduction of the computational demands. Numerical results, which are shown to be in very good agreement with those obtained by independent scientific research, indicate that the proposed technique can sufficiently handle this class of problems.

The purpose of this paper is to analyze a signal propagation in highly metalized environments, which has not been extensively studied in the literature. Having in mind a large number of such applications, better understanding and possibly finding a way of improving communication in these conditions would be highly beneficial.

The analysis is performed in a simulation environment developed by the authors, based on finite difference time domain (FDTD) method, to identify effects that have decisive influence on electromagnetic (EM) wave propagation in the aforementioned conditions. The analysis of the EM field at the reception is modified so that a multiple-field sampling is performed, and maximal values are further used. In practical realizations, this procedure could be implemented by using multiple antennas and selective combining at the reception.

Results show that the existence of metal objects (in the observed case, these are railway tracks), in combination with the appropriate choice of antenna parameters, can be favorably used to improve signal reception. The contribution is manifested through the reduction of the pathloss.

In the performed analysis, one should be aware of the limitations that the FDTD method brings. Those limitations are related to the size of the computational domain and discretization mesh refinement (possibility of modeling geometry in fine details).

Originality of this paper consists of the introduced modification in the analysis of signal propagation in heavily metalized environment. Namely, a multiple-field sampling in the reception zone (in one plane, dimensions λ × λ = 12.5 cm X 12.5 cm) is performed using several probes in simulation environment. In this way, a qualitative analysis is performed more efficiently, which made it is possible to distinguish and identify different propagation mechanisms.

The purpose of this paper is to describe the full‐wave modelling of pulsed terahertz systems utilized in non‐destructive testing.

At the outset, some basic information on the terahertz NDT are outlined and then, general remarks on its numerical modelling are presented. Frequency domain FEM and time domain FDTD analysis is carried out. Finally comparison of computed and measured signals is shown in order to prove numerical analysis correctness.

It is possible to model in a relatively simple way a terahertz system for nondestructive evaluation of dielectric materials. In contrast to other published work, the entire measuring setup is modelled, including photoconductive antenna with hemispherical lens, focusing lens and evaluated material with exemplary defect.

This paper gives a description of the terahertz non‐destructive testing system with comparison of simulated and measured results.

This paper aims to present a novel hybrid time integration approach for efficient numerical simulations of multiscale problems involving interactions of electromagnetic fields with fine structures.

The entire computational domain is discretized with a coarse grid and a locally refined subgrid containing the tiny objects. On the coarse grid, the time integration of Maxwell’s equations is realized by the conventional finite-difference technique, while on the subgrid, the unconditionally stable Krylov-subspace-exponential method is adopted to breakthrough the Courant–Friedrichs–Lewy stability condition.

It is shown that in contrast with the conventional finite-difference time-domain method, the proposed approach significantly reduces the memory costs and computation time while providing comparative results.

An efficient hybrid time integration approach for numerical simulations of multiscale electromagnetic problems is presented.

This paper presents a curvilinearly‐established finite‐difference time‐domain methodology for the enhanced 3D analysis of electromagnetic and acoustic propagation in generalised electromagnetic compatibility devices, junctions or bent ducts. Based on an exact multimodal decomposition and a higher‐order differencing topology, the new technique successfully treats complex systems of varying cross‐section and guarantees the consistent evaluation of their scattering parameters or resonance frequencies. To subdue the non‐separable modes at the structures' interfaces, a convergent grid approach is developed, while the tough case of abrupt excitations is also studied. Thus, the proposed algorithm attains significant accuracy and savings, as numerically verified by various practical problems.

The paper seeks to investigate the precise time‐domain modelling and broadband performance optimisation of 3D EMC structures formed by composite left‐handed metamaterials.

A frequency‐dependent alternating‐direction implicit finite‐difference time‐domain method is introduced. Developing a class of multi‐directional curvilinear schemes for double‐negative media, the unconditionally stable algorithm forms robust lattice tessellations and provides advanced models complicated media interfaces. Moreover, the erroneous refractions at the metamaterial boundaries are systematically analysed through dynamic stencil configurations and powerful perfectly matched layer absorbers.

The paper finds that the proposed technique leads to convergent discretisations that resolve all propagation bandwidths and enhances the design of promising periodical devices loaded by substrates of thin wires and split‐ring resonators. Furthermore, its versatile character subdues dispersion deficiencies far beyond the usual stability criteria. Numerical validation, addressing various up‐to‐date EMC devices like coupled antennas, waveguides, high‐pass filters and absorber linings in test facilities, confirms the merits of the algorithm.

The novel methodology offers an advanced nodal control process which drastically suppresses the serious dispersion errors of existing approaches as time‐step exceeds the Courant limit. The resulting grids can support coarse resolutions, while the general curvilinear framework, along with the ADI rationale, allows the accurate approximation of demanding permittivity and permeability constitutive profiles. Hence, high accuracy and confined computational overhead are achieved without the need of laborious assumptions.

The purpose of this paper is to develop a time implicit discontinuous Galerkin method for the simulation of two‐dimensional time‐domain electromagnetic wave propagation on non‐uniform triangular meshes.

The proposed method combines an arbitrary high‐order discontinuous Galerkin method for the discretization in space designed on triangular meshes, with a second‐order Cranck‐Nicolson scheme for time integration. At each time step, a multifrontal sparse LU method is used for solving the linear system resulting from the discretization of the TE Maxwell equations.

Despite the computational overhead of the solution of a linear system at each time step, the resulting implicit discontinuous Galerkin time‐domain method allows for a noticeable reduction of the computing time as compared to its explicit counterpart based on a leap‐frog time integration scheme.

The proposed method is useful if the underlying mesh is non‐uniform or locally refined such as when dealing with complex geometric features or with heterogeneous propagation media.

The paper is a first step towards the development of an efficient discontinuous Galerkin method for the simulation of three‐dimensional time‐domain electromagnetic wave propagation on non‐uniform tetrahedral meshes. It yields first insights of the capabilities of implicit time stepping through a detailed numerical assessment of accuracy properties and computational performances.

In the field of high‐frequency computational electromagnetism, the use of implicit time stepping has so far been limited to Cartesian meshes in conjunction with the finite difference time‐domain (FDTD) method (e.g. the alternating direction implicit FDTD method). The paper is the first attempt to combine implicit time stepping with a discontinuous Galerkin discretization method designed on simplex meshes.