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This paper focuses on the analysis of microstrip structures with graphene material as the conducting strip using two numerical methods, spectral domain technique and method of lines. The conductivity of graphene sheet is modeled in the analytical method using a tensor matrix. The results obtained from the above-mentioned methods are compared with those of commercial COMSOL modeling software. The structure is parametrically studied to investigate the effects of chemical potential and magnetic field bias on its behavior. The considered structures demonstrate attractive characteristics such as tunablility of dispersion and characteristic impedance as functions of chemical potential and magnetic bias, which can be used in new microwave applications. These characteristics have not been observed in the ordinary microstrip line structures.

• We present a rigorous method to evaluate the scattering of a plane electromagnetic wave by a perfectly conducting elliptic cylinder parallel to a generally reflecting plane surface. • The solution is based on the Spectral Domain method and the plane-wave expansion of the elliptical cylindrical waves. • The surface is characterized by means of a reflection coefficient. • The analytical method is implemented in specific computational code to achieve a numerical solution. • Results are validated by means of a finite element method commercial software. Validation trials, show good agreement between the two independent computational methodologies. In this paper, we present a rigorous analytical and numerical method to evaluate the scattering of a plane electromagnetic wave by an infinite, perfectly conducting elliptic cylinder parallel to a non-perfectly reflecting plane surface. The analytical solution is based on the spectral domain method and the plane-wave expansion of the elliptic cylindrical waves and is applicable in a broad variety of cases in which the properties of the plane surface may be expressed by means of a reflection coefficient. The proposed approach is suitably implemented in a specific computational code to achieve a numerical solution. Results of validation trials, performed by using finite element method commercial software, are provided. [ABSTRACT FROM AUTHOR]

The main objective of this work is the characterization of triangular array antenna with circular form by using the spectral domain technique. Firstly, the spectral domain formulation of single triangular patch antenna is given, in order to calculate its resonant frequencies and its radiation patterns. Then, we calculate and plot the total radiated field which is the multiplication of a single element radiation by the array factor, when patches are made in a circular arrangement. Comparing to the exiting array antenna design, the numerical results, obtained from the implementation of our calculations, have shown that the networking increases the gain, improves the directivity and controls the bandwidth with a compact form of the antenna arrangement. In addition the effects of different parameters of the structure on its performances are presented. [ABSTRACT FROM AUTHOR]

The propagation characteristics of a slotline structure under the influence of a static magnetic field have been studied using the model developed by Mark W. Coffey and John R. Clem. The complex valued resistive boundary condition formulated using the Coffey and Clem (CC) model is used to modify the dyadic Green's function in the spectral domain for the slot transmission line. The propagation characteristics are then calculated using the Galerkin's procedure. The numerical results are presented for propagation parameters and quality factor for a wide range of applied field, reduced temperature and superconducting layer thickness. The increase of the magnetic field and temperature causes an increase in vortex motion which results in a corresponding change in the propagation parameters and quality factor. The variation in the quality factor with respect to the superconducting strip thickness is explained using vortex effects. [ABSTRACT FROM AUTHOR]

A fast spectral-domain method is proposed to evaluate the reaction terms between the macro basis functions in regular and non-regular arrays made of identical printed antennas. The presented technique first exploits the filtering capabilities of the macro basis functions in the spectral domain. The method is then strongly accelerated with the help of a newly formulated fast Fourier transform (FFT)-based technique, which is applicable to a contour integration in the complex plane. We name the method as contour-FFT (C-FFT). Besides an effective homogeneous medium term treated with multipoles, a computational complexity of order N\log2N is achieved for the tabulation of substrate-related reaction terms for any possible relative positions. The complexity of the proposed method is independent from the complexity of the elements. Numerical results obtained with the proposed method are compared with those from a pre-validated reference solution based on the traditional macro basis functions technique; an excellent agreement is observed. [ABSTRACT FROM PUBLISHER]

The electromagnetic field transmitted by a subwavelength circular aperture in a perfectly conducting screen of infinitesimal thickness and illuminated by an obliquely incident plane wave is analyzed based on the Bethe–Bouwkamp quasi-static model of the field in the aperture plane. The problem is formulated in the spectral domain and the solution is expressed in terms of a minimum number of one-dimensional Hankel-transform integrals involving products of Bessel functions and spherical Bessel functions. An efficient computational scheme for these integrals is implemented, based on numerical quadrature with convergence acceleration by extrapolation. From the rigorous spectral domain formulation, closed form expressions are also derived for the transmitted near-zone and far-zone fields. Sample numerical results are presented to demonstrate the validity of the method and its utility in the modeling of aperture-type near-field optical probes. [ABSTRACT FROM PUBLISHER]

In this paper, we investigate the spectral method that calculates the S-parameters for microstrip circuits and antennas. A sampling interval selection criterion is proposed. The scheme for low-loss cases is specially discussed. Several examples are employed to demonstrate the engineering applications of the spectral domain method and its results are compared with previously published and measured results. [ABSTRACT FROM AUTHOR]

Abstract: Interdigitated electrodes represent a commonly used planar structure when it comes to implementing capacitive sensors. The electric field decays strongly in the surface normal direction of the electrode arrangement. This can be used to estimate the thickness of dielectric films residing on the electrodes. A simple example for an application would be the detection of the build-up of biofilms. The exact expressions for the capacitance are relatively complex and can be provided in closed form only for the case without a cover layer. In this contribution we present an efficient modeling approach based on a physically motivated approximation of the charge distribution on the electrodes. Establishing a closed-form spectral domain representation of the associated electric potential distribution allows a numerically highly efficient calculation of the capacitance utilizing the FFT algorithm. In contrast to previous works, additional cover layers can be easily included in the model, which allows studying the aforementioned sensing effect. [Copyright &y& Elsevier]

In this article, the spectral domain method of moment is utilized to analyze frequency selective surface with RWG basis functions for arbitrarily shaped metal geometry. The Fourier transform of the RWG basis function can be expressed in the analytical form and the fast convergence characteristic can reduce the computation time of impedance matrix. Some examples are calculated to demonstrate the efficiency of the proposed method. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2567–2570, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24674 [ABSTRACT FROM AUTHOR]

The Method of the Weighted Residuals (MWR), sometimes known as the Method of Moments (MoM), has traditionally been applied in the frequency domain and has been shown to be effective and efficient, especially in computing open electromagnetic structure problems. Although it has been extended to the time domain in various forms, it is generally employed to solve integral formulations derived from Maxwell's equations. Therefore, it is often considered to be one type of numerical method that is different from other numerical methods, such as finite-difference methods. However, in this paper we will show that the MWR, or MoM, is not just a method per Se: it can in fact be a general framework for or approach to unifying or deriving most of the numerical methods developed so far, either in the frequency domain or in the time domain. As a result, all numerical methods can be quite easily understood and can be categorized in one general method, although their conventional derivations may still have their respective advantages. One potential application is that the hybridization of different numerical methods can now be done within a uniform framework. The paper is intended for both beginners and experienced practitioners in the area of numerical electromagnetic modeling. [ABSTRACT FROM AUTHOR]

The article studies the dispersive characteristics of multilayered bilateral anisotropic coplanar waveguide couplers for both electric and magnetic wall symmetries using the spectral domain method. The authors extend the immittance-approach method to multilayered structures through a recursive process that takes into account the anisotropy of the material to derive the dyadic-admittance Green's function for both open and shielded couplers.

The dispersive characteristics of multilayer microstrip structures with one thin metallic substrate are studied using the spectral-domain approach. The numerical results of several approximate models are compared with that of the immittance approach as one exact model. The comparison shows that the widely used resistive sheet (R-card) model is not appropriate to handle such structures over a broad frequency range. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1113–1117, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21556 [ABSTRACT FROM AUTHOR]

Multilayer microstrip lines are an integral part of MMIC. This paper presents an analysis of multilayer GaAs microstrip lines using a spectral-domain method (SDM), taking into account the effect of the variation in the thickness of various layers of substrates on the characteristic impedance and the effective dielectric constant of the line. Some of the theoretical results are validated by the measured results on three-layer GaAs microstrip lines, showing a close agreement within a 1% deviation over a large frequency range up to 20 GHz. The proposed CAD model is expected to provide an economical and fast CAD procedure for GaAs-MMIC foundries. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 159–162, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11156 [ABSTRACT FROM AUTHOR]

If it is possible to derive the complex permittivity of a dielectric material by measurement of the coefficient of reflection from the aperture of a flanged rectangular waveguide attached to a conductor-backed lossy dielectric sheet, an effective nondestructive measurement method can be established. In this paper, by solving simultaneous equations derived by an application of the spectral domain method, contour maps for derivation of the complex permittivity of a lossy dielectric from the reflection coefficient are formed and their characteristics are studied. The effectiveness of these contour maps is confirmed by experiments. In the region within the contour chart where the permittivity can be determined with good accuracy, it can be determined with an error of about 5% by means of a general-purpose network analyzer. Further, the attenuation of the electromagnetic wave within the lossy dielectric in the direction of propagation is studied in order to derive the dimensions of the sample and flange needed for actual measurement. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(4): 59–67, 2001 [ABSTRACT FROM AUTHOR]

An efficient computer technique based on the spectral domain method is presented to solve the problem of modeling coplanar gap discontinuity. Comparison with available published data is done to confirm the accuracy of the method. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 150–158, 2000. [ABSTRACT FROM AUTHOR]

This paper considers the problem of scattering of electromagnetic waves by a strip conductor when the source is a line current source or a line magnetic current source. The problem is analyzed as a two-dimensional boundary value problem when the strip conductor thickness is negligibly thin and the distance from the center of the strip to the source is larger than one-half its width. The expansion functions of the current are selected to satisfy the edge condition. By means of the spectral domain method, the simultaneous equations for the expansion coefficients and the specific expressions for the coefficients are derived. The current distributions and the scattered far field are computed numerically. In the analysis process, it is shown that the coefficients derived are identical to those of the simultaneous equations in the analysis for the plane wave incidence making use of the Weber-Schafheitlin discontinuous integral. [ABSTRACT FROM AUTHOR]

Abstract The main objective of this work is the characterization of triangular array antenna with circular form by using the spectral domain technique. Firstly, the spectral domain formulation of single triangular patch antenna is given, in order to calculate its resonant frequencies and its radiation patterns. Then, we calculate and plot the total radiated field which is the multiplication of a single element radiation by the array factor, when patches are made in a circular arrangement. Comparing to the exiting array antenna design, the numerical results, obtained from the implementation of our calculations, have shown that the networking increases the gain, improves the directivity and controls the bandwidth with a compact form of the antenna arrangement. In addition the effects of different parameters of the structure on its performances are presented.