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Article
Publication date: 14 November 2008

Sebastian Emanuel Lauro, Filiberto Bilotti, Alessandro Toscano and Lucio Vegni

To devise a parametric study using a new application of the boundary element method (BEM) and to propose an efficient approach for speeding up the computation time of the…

Abstract

Purpose

To devise a parametric study using a new application of the boundary element method (BEM) and to propose an efficient approach for speeding up the computation time of the BEM based on neural networks (NNs).

Design/methodology/approach

A 3D finite elements formulation is combined with radial basis function NNs to speeding up the computation time.

Findings

The paper shows how to estimate the role of thin slabs filled with unconventional media in order to increase the coupling values when placed between two metallic strips in a coupled microstrip line layout or to improve the shielding properties when used as absorber.

Research limitations/implications

The numerical results here presented are not bianisotropic but can be easily extended to take into account bianisotropic media.

Originality/value

The formulation is one of the only with the potential for investigating unconventional bianisotropic media like Chiral materials which are seen as one possible route to achieving double negative media.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Content available
Article
Publication date: 14 November 2008

Mauro Feliziani, Alessandro Salvini, Alessandro Toscano and Lucio Vegni

364

Abstract

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Article
Publication date: 11 November 2013

Alessio Monti, Luca Scorrano, Simone Tricarico, Filiberto Bilotti, Alessandro Toscano and Lucio Vegni

The purpose of this paper is to show how metamaterials with extreme values of permittivity and permeability, may be effectively used to design artificial magnetic…

Abstract

Purpose

The purpose of this paper is to show how metamaterials with extreme values of permittivity and permeability, may be effectively used to design artificial magnetic conductors (AMC) at a given frequency. In particular, this paper theoretically determines, for the different polarizations of the incidence field, the conditions under which metamaterials can behave as an AMC.

Design/methodology/approach

In order to find out the required values of the constitutive parameters, this paper has done a theoretical analysis based on the transmission-line theory. The obtained analytical reflection coefficient has been particularized for the different possible polarizations of the incidence field in order to find the constitutive parameters values that this paper needs for the AMC behavior.

Findings

Depending on the polarization of the field, it is shown that different values of the constitutive parameters are needed to get AMCs. In particular, it is shown that in the case of TEM and TE polarizations, a large value of the permeability is enough to obtain an AMC boundary condition. In the case of the TM polarization, instead, the AMC boundary condition is effectively achieved by using a material with vanishing permittivity. The role of the permittivity in the three polarizations is discussed. Finally, possible implementations and applications at microwave and optical frequencies are presented.

Originality/value

The idea of using miniaturized inclusions to obtain AMCs is not completely new. However, to the authors' best knowledge, a complete and rigorous theoretical analysis showing the capabilities and the limits of this approach has not yet been presented in the open technical literature.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 11 November 2013

Davide Ramaccia, Filiberto Bilotti, Alessandro Toscano and Lucio Vegni

– The purpose of this paper is to design simple and high-performing screens capable to separate circularly polarized electromagnetic waves in Ku band from the ones in Ka band.

Abstract

Purpose

The purpose of this paper is to design simple and high-performing screens capable to separate circularly polarized electromagnetic waves in Ku band from the ones in Ka band.

Design/methodology/approach

The proposed screen consists of an inductive double resonant element FSS, i.e. a regular array of circular holes in a metal thick plate, in order to grant the robustness to mechanical stress for antenna applications in extreme conditions.

Findings

The proposed design of a multi-band frequency selective surface (FSS) is able to separate circularly polarized electromagnetic waves in Ku band from the ones in Ka band.

Originality/value

The paper shows the capabilities of a novel FSS that combine the transmission properties of two simple FSSs which allows us to achieve an interesting behaviour in three typical bands of the satellite communications.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 11 November 2013

Kamil Boratay Alici, Mehmet Deniz Caliskan, Filiberto Bilotti, Alessandro Toscano, Lucio Vegni and Ekmel Ozbay

Metamaterial unit cells composed of deep subwavelength resonators brought up new aspects to the antenna miniaturization problem. The paper experimentally demonstrates a…

Abstract

Purpose

Metamaterial unit cells composed of deep subwavelength resonators brought up new aspects to the antenna miniaturization problem. The paper experimentally demonstrates a metamaterial-inspired miniaturization method for circular patch antennas. In the proposed layouts, the space between the patch and the ground plane is filled with a proper metamaterial composed of either multiple split-ring or spiral resonators (SRs). The authors have manufactured two different patch antennas, achieving an electrical size of λ/3.69 and λ/8.26, respectively. The paper aims to discuss these issues.

Design/methodology/approach

The operation of such a radiative component has been predicted by using a simple theoretical formulation based on the cavity model. The experimental characterization of the antenna has been performed by using a HP8510C vector network analyzer, standard horn antennas, automated rotary stages, coaxial cables with 50 Ω characteristic impedance and absorbers. Before the characterization measurements we performed a full two-port calibration.

Findings

Electrically small circular patch antennas loaded with single layer metamaterials experimentally demonstrated to acceptable figures of merit for applications. The proposed miniaturization technique is potentially promising for antenna applications and the results presented in the paper constitute a relevant proof for the usefulness of the metamaterial concepts in antenna miniaturization problems.

Originality/value

Rigorous experimental characterization of several meta material loaded antennas and proof of principle results were provided.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 14 November 2008

S. Coco, A. Laudani, F. Riganti Fulginei and A. Salvini

The aim of this work is to show how evolutionary computation can improve the quality of 3D‐FE mesh that is a crucial task for field evaluations using 3‐D FEM analysis.

Abstract

Purpose

The aim of this work is to show how evolutionary computation can improve the quality of 3D‐FE mesh that is a crucial task for field evaluations using 3‐D FEM analysis.

Design/methodology/approach

The evolutionary approach used for optimizing 3D mesh generation is based on the bacterial chemotaxis algorithm (BCA). The objective function corresponds to the virtual bacterium best habitat, and the motion rules followed by each virtual bacterium are inspired to the natural behaviour of bacteria in real habitat.

Findings

The obtained results show that the present approach returns good accuracy performances with low‐computational costs.

Practical implications

The procedure is robust and converges for all the practical cases examined for validation.

Originality/value

The adoption of a correct optimization algorithm is fundamental to obtain good performances in terms of robustness of the results and the low‐computational costs. In this sense, the BCA is a valid instrument for improving the quality of 3D‐FE mesh.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 14 November 2008

Salvatore Coco, Antonino Laudani and Giuseppe Pollicino

The paper's aim is to focus on the utilization of the GRID distributed computing environment in order to reduce simulation time for parameter studies of travelling wave…

Abstract

Purpose

The paper's aim is to focus on the utilization of the GRID distributed computing environment in order to reduce simulation time for parameter studies of travelling wave tube (TWT) electron guns and helix slow‐wave structures.

Design/methodology/approach

Two TWT finite‐element analysis modules were adapted to be run on the GRID, for this purpose scripts were written to submit a collection of independent jobs (the parameter study) to the GRID and collect the results.

Findings

A 25‐job electron gun parameter study runs on the GRID in 30‐40 min instead of 7 h locally. A 16‐job slow‐wave structure parameter study runs in 1 h on the GRID instead of 8 h locally. Turnaround time on the GRID was limited by priority levels presently set by GRID management for the various jobs submitted.

Practical implications

The procedures guarantee a remarkable reduction of the computing time.

Originality/value

For heavy‐computational cost tasks such as the above finite element electromagnetic calculations, the effective use of a heterogeneous, distributed, computing platform (the GRID computing platform) is very advantageous. The paper shows the development of new generation collaborative tools.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 14 November 2008

Carlos Alberto Ferreira Fernandes

The aim of this paper is to develop simulation tools for the analysis of modified structures of distributed feedback (DFB) laser diodes adequate for single longitudinal…

Abstract

Purpose

The aim of this paper is to develop simulation tools for the analysis of modified structures of distributed feedback (DFB) laser diodes adequate for single longitudinal mode (SLM) operation.

Design/methodology/approach

The paper uses matricial techniques: the transfer matrix method (TMM). When compared to the eigenvalue approach, the matricial techniques are more general and flexible and hence are especially adequate to deal with the analysis and structural design of DFB laser diodes. In this work, the author makes a general description of the TMM, enhancing its importance with some applications by considering the threshold and above‐threshold analysis of a modified DFB laser structure.

Findings

The increasing demands on laser performance, mainly in the area of optical communication systems, have lead to the fabrication of more‐and‐more complex structures. In viewing the development of the associated technology, the importance of the simulation tools revealed of crucial importance.

Originality/value

The simulation model used in this work has been described in other works of the author. In the present analysis a general description of the TMM was implemented, summarizing the results of previous studies for the threshold and above‐threshold regimes of modified DFB laser structures specially designed to show SLM operation.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 14 November 2008

B. Vahidi, B. Hemmatian and S.H. Hosseinian

To find an easy and accurate method for evaluating the Pollaczek's integral in earth‐return path impedance calculation.

347

Abstract

Purpose

To find an easy and accurate method for evaluating the Pollaczek's integral in earth‐return path impedance calculation.

Design/methodology/approach

The Monte Carlo method of evaluating the Pollaczek's integral is introduced.

Findings

The Monte Carlo method is easy and accurate method for this computation.

Research limitations/implications

Using proposed method in cases of earth stratification.

Practical implications

The proposed method can be used in power system transient software.

Originality/value

The proposed method introduces a computation method for calculation of Pollaczek's integral which is valuable for power engineers.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 14 November 2008

Concettina Buccella, Valerio De Santis, Mauro Feliziani and Piero Tognolatti

The paper aims to propose a three‐dimensional (3D) finite element analysis to evaluate the electrical performances of a FBAR (thin‐film bulk acoustic resonator) resonator.

Abstract

Purpose

The paper aims to propose a three‐dimensional (3D) finite element analysis to evaluate the electrical performances of a FBAR (thin‐film bulk acoustic resonator) resonator.

Design/methodology/approach

The piezoelectric theory that uses an equivalent circuit is able to evaluate the thickness‐extensional vibration modes in simple 1D configuration but it is not adequate to predict spurious modes with lateral wave vector. Therefore, a fully 3D finite element analysis has been carried out to evaluate the characteristics of a real FBAR prototype that has been fabricated in a research center.

Findings

The measured characteristics of the FBAR prototype are compared with simulations obtained by the 3D finite element analysis. The agreement between experimental and numerical results confirms the accuracy of the proposed technique.

Originality/value

The paper proposes a 3‐D numerical approach to design and analyze the electrical characteristics of a real FBAR which has been fabricated following the guidelines obtained by the proposed numerical design.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

1 – 10 of 29