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In this paper, we report on a dielectric study of a series of composite systems based upon a polystyrene matrix (έm ∼2.7) containing dispersed particles of lead zirconate titanate (PZT) and barium titanate (BaTiO3) (in both cases, έp ∼1000). These components were chosen to give a high dielectric contrast within the system and, because polystyrene is readily etched using permanganic reagents, the size...
This paper discusses numerical properties of volume integral equation formulations in electromagnetic scattering by isotropic, anisotropic and bi-anisotropic objects. The volume integral equation formulation written in terms of the volume current densities and discretized with element-wise defined discontinuous functions is found to lead to more robust and efficient solutions on a wide range of material...
This paper explores the effective permittivity and permeability of the structure which has periodic lossy dielectric objects embedded in a matrix. The asymptotic expressions for both high conductivity and quasi-static are derived and discussed. Numerical results both from the MG formula and an integral equation approach are provided to verify all the asymptotic expressions and related conclusions.
The systropic sphere is a spherical scatterer whose axes of anisotropy are defined by spherical coordinates. This contribution discusses the electrostatic scattering from a systropic sphere with extreme material parameters. The permittivity divides into three component in the spherical coordinates. Larger component values produce more polarizability, but there is a limit to the increase of the polarizability...
This paper is part of a larger project which aims to investigate the fabricational and electromagnetic advantages of creating integrated antenna systems using emerging nano-manufacturing technology. It has been known for several decades that the effective permittivity of a mixture consisting of dielectric inclusions in a host dielectric can be controlled by varying the permittivity, size and spacing...
This paper explains in details the NRW method highlighting its mathematical procedure and analyzing the most important points and limitations to characterize the complex permittivity and permeability of dielectrics. The step by step procedure help the researchers to well understand the physical phenomenona involved and also is a tool to facilitate its implementation. Explanations on the limitations...
Accurate material modeling is an important factor in simulation of dispersive materials. We present different dispersive models for the simulation of dispersive materials, and can be used from microwave to optical frequencies depending on the nature of application. Most of available dispersive models are in frequency domain, to make them consistent with time domain methods; different approaches are...
A generalized formulism has been derived from an equivalent circuit model for describing the effective permittivity of an artificial material composed of dumbbell-shaped metal particles embedded periodically in a host dielectric medium. Theoretical value of effective permittivity compare well with numerical results obtained from HFSS simulation. The work shows that artificial material can achieve...
An analytical study of heterogeneous substrates created by including small particles arranged in a cubic lattice within a host medium is presented in this paper. Rapid advances in nanomaterial fabrication techniques will allow in the near future, heterogeneous samples to be created with nano or micro-sized inclusions, and this paper investigates the electromagnetic (EM) properties of these structures...
An analytical study of artificial materials created by embedding spherical nano-particles in an infinite homogenous medium is presented in this paper. Propositions by various contributors to this area of the nanomaterials' field have been compared with respect to their approaches in finding the effective constituent parameters, over wide frequency ranges. Their closed form equations were examined...
This work aims to analyze the effects of dielectric materials and its characteristics in electric fields. Considering the field propagation inside the dielectrics and its permittivity dependency, were done experimental tests, in order to observe the electric fields perturbations in a presence of wood. The tests were done in half anechoic chamber of Fiat Automveis, and the results pointed to a field...
There is a growing interest to verify the dielectric mixing rules and to provide a general model for composites. This paper presents a study to estimate the effective dielectric constant of two-phased composites with lossless dielectric constant using the 2D finite difference frequency domain algorithm.. The simulations showed very close agreement to theoretical mixing rules with some small deviation...
The new method of significant reducing the temperature coefficient of delay (TCD) for acoustoelectronic devices based on thin piezoelectric plates was suggested. On the example of the SH0 waves propagating in the structure “plate YX lithium niobate-vacuum gap-semi-infinite dielectric medium” the change of the output signal phase as function of the medium permittivity and value of vacuum gap was analyzed...
The multiscale FEM is used to analysis the problem that wave propagates in a period media. The equation of EM wave for multisacle FEM is deduced. The two dimensional wave propagation problem is solved. The computed results are compared with results which are computed by conventional FEM. The two result agree with well.
A number of mixing rules are proposed in the literature to predict the dependence of effective material parameters of composites, the permittivity and permeability, on frequency and concentration. Alternatively to the mixing rules, properties of composites can be considered in terms of the Bergman-Milton theory (BMT), which employs the concept of the spectral function. All known mixing rules are particular...
Engineering of absorbing bulk and sheet composite materials, including nanocomposites, for various EMI applications, requires adequate prediction of frequency and concentration behavior of these composites. This paper proposes two simple analytical formulations for effective permittivity and permeability of magneto-dielectric composites as functions of frequency and concentration. The first new proposed...
This paper investigates how the number of terms used in a multi-term Debye material model impact the accuracy of the computed complex propagation constant in low loss printed circuit boards.
This paper presents the values of effective complex permittivity for a corrugated slab whose corrugations are either an array of dielectric pillars in free space or an array of cavities in a dielectric slab, depending on whether the host material is free space and the inclusions are dielectric (pillar corrugations), or whether the host material is dielectric and the inclusions are free space (cavity...
In the frequency-domain modeling of physical systems, such as electric circuits and electromagnetic-field structures, the problem of maintaining the causality of the time-domain response is an important issue in many engineering applications. The aim of the paper is to revisit some models for media parameters, transmission lines, and circuits.
The effect of electron beam radiation on permittivity of polymethyl methacrylate (PMMA) samples is investigated. Experimental results show that the variance of permittivity in irradiated PMMA is mainly determined by two factors. One is porosity of the material. The irradiating process increases the porosity due to the escape of the small molecule (e.g. CO, CO2, CH4 etc.) produced by material degradation...
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