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Lara Pajewski

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10

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Fabrizio Frezza

Università degli Studi "La Sapienza" di Roma

Burak Temelkuran

Université Paris Nanterre

Inha University

Ecole Nationale d'Ingénieurs de Tunis (ENIT)

Ruhr-Universität Bochum

Sergey L Prosvirnin

V.N. Karazin Kharkiv National University

Bhuvneshwer Suthar

Other

University of Adelaide

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Papers by Lara Pajewski

Numerical investigation on the filtering behavior of 2-D PBGs with multiple periodic defects

IEEE Transactions on Nanotechnology, 2005

In this study, the transmission properties of photonic crystals with multiple periodic defects ar... more In this study, the transmission properties of photonic crystals with multiple periodic defects are studied by using a fullwave approach. The high convergence rate of the employed technique has allowed us to accurately and efficiently predict the filtering behavior of the considered structures. Results are presented for both TE and TM polarizations, showing the transmission efficiencies as a function of the involved parameters. In order to give more physical insight, a comparison with a simpler one-dimensional model has been provided. From our numerical investigation, it turns out that, by suitably configuring the photonic bandgap, it is possible to shape the filtering properties in TE polarization in a simple and versatile way.

$Research paper thumbnail of Characterization and design of two-dimensional electromagnetic band-gap structures by use of a full-wave method for diffraction gratings$

Characterization and design of two-dimensional electromagnetic band-gap structures by use of a full-wave method for diffraction gratings

IEEE Transactions on Microwave Theory and Techniques, 2003

In this paper, an accurate and efficient characterization of a two-dimensional (2-D) electromagne... more In this paper, an accurate and efficient characterization of a two-dimensional (2-D) electromagnetic band-gap (EBG) structures is performed, which exploits a full-wave diffraction theory developed for one-dimensional diffraction gratings. EBG materials constituted by 2-D arrays of dielectric rods with arbitrary shape and lattice configuration are analyzed, and the transmission and reflection efficiencies are determined. The high convergence rate of the proposed technique is demonstrated. Results are presented for both TE and TM polarizations, showing the efficiencies as a function of frequency and physical parameters. Comparisons with other theoretical results reported in the literature are shown with a very good agreement, and the authors' theory is also favorably compared with available experimental data. Useful design contour plots are reported by which a very immediate and accurate visualization of the band-gap configurations can be obtained, and design formulas are also included. Finally, the behavioral differences when a periodical defect is present are also highlighted.

Design and fabrication of a 3D-EBG superstrate for patch antennas

A layer-by-layer electromagnetic band-gap (EBG) structure has been fabricated by means of alumina... more A layer-by-layer electromagnetic band-gap (EBG) structure has been fabricated by means of alumina rods with square cross-section. The rods have been placed to form a woodpile structure; a square support with thin iron pins has been employed to obtain a precise rods alignment. The design parameters have been chosen to make the structure resonate at 11 GHz, when two identical woodpile layers are employed to form an EBG cavity. At the resonance, a unitary transmission occurs for an incident field, which can be employed in many microwave applications. In particular, a patch antenna has been fabricated to be used with the woodpile cavity, with properties of high directivity.

FMM and FDTD analysis of a woodpile 3D-EBG superstrate for patch antennas

Microwave and Optical Technology Letters, 2006

A fast and accurate modeling of the transmission and reflection properties of 3D-EBGs can be perf... more A fast and accurate modeling of the transmission and reflection properties of 3D-EBGs can be performed by exploiting a Fourier modal method (FMM), which in the literature is regarded as the most efficient and prevailing rigorous technique for the analysis of doubly-periodic gratings. Putting a woodpile EBG superstrate on a customary microstrip-patch feed, an antenna with highly directional radiation pattern can be obtained. The ensemble constituted by the perfectly conducting plane and the woodpile EBG can be schematized by means of an equivalent resonating all-dielectric structure, which has been studied by using our FMM tool for 3D-EBGs. Subsequently, the behavior of the whole radiating device has been checked with a finite difference time domain technique. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2595–2598, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21991

Full-Wave Characterization of Three-Dimensional Photonic Bandgap Structures

IEEE Transactions on Nanotechnology, 2006

In this paper, an accurate and efficient characterization of three-dimensional electromagnetic ba... more In this paper, an accurate and efficient characterization of three-dimensional electromagnetic bandgap (3D-EBG) structures is performed, which exploits a full-wave theory developed for doubly periodic gratings. The theoretical approach is presented, details on the numerical implementation are given, and the potentiality of the method in the analysis and design of EBGs is discussed. Convergence figures are reported and comparisons with both theoretical data available in the literature and in-house FDTD data are shown, with a very good agreement. Results are presented for EBGs with cubic inclusions, plots of the transmission efficiency as a function of geometrical and physical parameters are reported and commented on.

Fractal two-dimensional electromagnetic bandgap structures

IEEE Transactions on Microwave Theory and Techniques, 2004

Fractal two-dimensional electromagnetic bandgap (EBG) materials are proposed and studied by means... more Fractal two-dimensional electromagnetic bandgap (EBG) materials are proposed and studied by means of a full-wave method developed for diffraction gratings. Such technique allows us to characterize, in an accurate and rapidly convergent way, the transmission and reflection properties of periodic fractal structures with an arbitrary geometry in the unit cell. Both polarization cases can be treated. A validation of the employed method is performed through a comparison with theoretical results and experimental data taken from the literature; the convergence properties of our method when applied to fractal EBG materials are checked. In particular, three different fractal EBGs are considered here. Numerical results are reported for the transmission efficiency as a function of the frequency and the incidence angle. Typical effects due to the fractal geometry are observed, like multiband behavior and enlargement of stopbands.

Periodic defects in 2D-PBG materials: full-wave analysis and design

IEEE Transactions on Nanotechnology, 2003

In this paper, an accurate and efficient characterization of two-dimensional photonic bandgap str... more In this paper, an accurate and efficient characterization of two-dimensional photonic bandgap structures with periodic defects is performed, which exploits a full-wave diffraction theory developed for one-dimensional gratings. The high convergence rate of the proposed technique is demonstrated. Results are presented for both TE and TM polarizations, showing the efficiencies as a function of wavelength, incidence angle, geometrical and physical parameters. A comparison with other theoretical results reported in the literature is shown with a good agreement. The transmission properties of photonic crystals with periodic defects are studied, investigating the effects of the variation of geometrical and physical parameters; design efficiency maps and formulas are given; moreover, the application of the analyzed structures as filters is discussed.

Plane-wave expansion of cylindrical functions in lossy media

Optics Communications, 2006

Cylindrical waves, expressed as the product of a Hankel function of integer order times a sinusoi... more Cylindrical waves, expressed as the product of a Hankel function of integer order times a sinusoidal angular factor, are often employed in the solution of two-dimensional scattering problems. In this paper, a general closed-form expression for the angular spectrum of a cylindrical wave in a lossy medium is derived.

Scattering by Perfectly Conducting Circular Cylinders Buried in a Dielectric Slab Through the Cylindrical Wave Approach

IEEE Transactions on Antennas and Propagation, 2009

AbstractAn analytical-numerical technique for the solution of the plane-wave scattering problem ... more

Fast and accurate modeling of finite-thickness 2D-EBG structures made by circular-section rods

Microwave and Optical Technology Letters, 2003

In this paper, electromagnetic crystals constituted by 2D arrays of dielectric rods with a circul... more In this paper, electromagnetic crystals constituted by 2D arrays of dielectric rods with a circular cross section and rectangular-lattice configuration are analyzed, and the transmission and reflection efficiencies are determined. The high convergence rate of the proposed technique is demonstrated. Results are presented for both TE and TM polarizations, showing the efficiencies as a function of physical and geometrical parameters. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 433–437, 2003

A Spectral-Domain Solution for the Scattering Problem of aCircular Cylinder Buried in a Dielectric Half-Space

Progress in Electromagnetics Research-pier, 2002

A spectral-domain solution is employed to completely characterize the twodimensional electromagne... more A spectral-domain solution is employed to completely characterize the twodimensional electromagnetic plane-wave scattering problem by a perfectly conducting circular cylinder buried in a possibly lossy dielectric half-space. Use is made of the plane-wave spectrum to consider the di®raction, re°ection and transmission of cylindrical waves. Suitable adaptive integration techniques are employed to numerically solve the spectral integrals. The method is valid for any value of the cylinder radius, and of the distance between the cylinder and the interface.

Full-Wave Analysis of the Optimum Triplicator

Journal of Electromagnetic Waves and Applications, 2001

Starting from the results obtained in the scalar domain for the diffractive optical element that ... more Starting from the results obtained in the scalar domain for the diffractive optical element that produces three equi-intense diffraction orders with the maximum efficiency, we present a full-wave electromagnetic treatment of such optimum triplicator. The performances of this element are studied in the resonance domain and in the scalar limit as far as the dependence on the grating period, the

Scattering by buried dielectric cylindrical structures

Radio Science, 2005

1] An analytical-numerical technique for the solution of the two-dimensional electromagnetic plan... more 1] An analytical-numerical technique for the solution of the two-dimensional electromagnetic plane wave scattering by a finite set of dielectric circular cylinders buried in a dielectric half-space is presented. The problem is solved for both the near-and far-field regions, for transverse magnetic and transverse electric polarizations. The scattered field is represented in terms of a superposition of cylindrical waves, and use is made of the plane wave spectrum to take into account the reflection and transmission of such waves by the interface. The validity of the approach is confirmed by comparisons with results available in the literature, with very good agreement, and by self-consistency tests. Applications of the method to objects of arbitrary cross section simulated by suitable configurations of circular cylinders are shown. Citation: Di Vico, M., F. Frezza, L. Pajewski, and G. Schettini (2005), Scattering by buried dielectric cylindrical structures,

Scattering by a finite set of perfectly conducting cylinders buried in a dielectric half-space: a spectral-domain solution

IEEE Transactions on Antennas and Propagation, 2005

An analytical-numerical technique, for the solution of the two-dimensional electromagnetic plane-... more An analytical-numerical technique, for the solution of the two-dimensional electromagnetic plane-wave scattering by a finite set of perfectly conducting circular cylinders buried in a dielectric half-space, is presented. The problem is solved for both the near-and the far-field regions, for TM and TE polarizations. The diffracted field is represented in terms of a superposition of cylindrical waves and use is made of the plane-wave spectrum to take into account the reflection and transmission of such waves by the interface. The validity of the approach is confirmed by comparisons with results available in the literature, with very good agreement. The multiple interactions between two buried cylinders have been studied by considering both the induced currents and the scattered field diagrams. Applications of the method to objects of arbitrary cross-section simulated by a suitable configuration of circular cylinders are shown.

Design of a Binary Grating with Subwavelength Features that Acts as a Polarizing Beam Splitter

Applied Optics, 2001

A binary diffractive optical element, acting as a polarizing beam splitter, is proposed and analy... more A binary diffractive optical element, acting as a polarizing beam splitter, is proposed and analyzed. It behaves like a transmissive blazed grating, working on the first or the second diffraction order, depending on the polarization state of the incident radiation. The grating-phase profile required for both polarization states is obtained by means of suitably sized subwavelength groups etched in an isotropic dielectric medium. A rigorous electromagnetic analysis of the grating is presented, and numerical results concerning its performances in terms of diffraction efficiency as well as frequency and angular bandwidths are provided.

$Fig. 12. Average diffraction efficiencies of the transmitted orders TE, (filled circles) and TM, (open circles) plotted as functions of the maximum amplitude 6; of the random fabrication error for d, = 0.05d (M = 20).$

Modeling of three-dimensional electromagnetic band-gap structures

Cylindrical-wave approach for the electromagnetic scattering problem by buried two-dimensional objects

Journal of Applied Geophysics, 2009

The Cylindrical-Wave Approach (CWA) rigorously solves, in the spectral domain, the electromagneti... more The Cylindrical-Wave Approach (CWA) rigorously solves, in the spectral domain, the electromagnetic forward scattering by a finite set of buried two-dimensional perfectly-conducting or dielectric objects [1]- . In this technique, the field scattered by underground objects is represented in terms of a superposition of cylindrical waves. Use is made of the plane-wave spectrum [1] to take into account the interaction of such waves with the planar interface between air and soil, and between different layers eventually present in the ground.

Short-Pulse Electromagnetic Scattering by Buried Perfectly Conducting Cylinders

IEEE Geoscience and Remote Sensing Letters, 2007

In this letter, the electromagnetic scattering problem of a short-pulse plane wave by a finite se... more In this letter, the electromagnetic scattering problem of a short-pulse plane wave by a finite set of buried perfectly conducting circular cylinders is addressed in the time domain. The described procedure is applicable for arbitrary polarization and for any cylinder size and configuration in both near- and far-field regions. The solution is performed through an angular-spectrum representation of the scattered field. A parametric analysis on the effects of the various geometrical parameters is reported, and numerical results are presented.

FDTD Analysis of EBG Superstrates

Radiating devices, made up by woodpile electromagnetic bandgap (EBG) material superstrates placed... more Radiating devices, made up by woodpile electromagnetic bandgap (EBG) material superstrates placed over microstrip patches, are taken in consideration. Much interest is devoted to such antennas because of their enhanced directivity. The radiated far field has been calculated using an in- house finite-difference time-domain (FDTD) code. The microstrip position has been changed and the woodpile superstrate has been rotated: the

Application of a woodpile superstrate for directivity enhancement of antennas

Compel-the International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2008

Purpose – The purpose of this paper is to investigate the role of electromagnetic band-gap (EBG) ... more Purpose – The purpose of this paper is to investigate the role of electromagnetic band-gap (EBG) materials in the enhancement of antennas&amp;amp;amp;amp;amp;amp;#39; directivity. Design/methodology/approach – An analysis of a woodpile EBG material is performed, which points out its band properties. Woodpile cavities are then considered, obtained by interrupting the periodicity of the crystal. A woodpile cavity is then superimposed to

Numerical investigation on the filtering behavior of 2-D PBGs with multiple periodic defects

IEEE Transactions on Nanotechnology, 2005

In this study, the transmission properties of photonic crystals with multiple periodic defects ar... more In this study, the transmission properties of photonic crystals with multiple periodic defects are studied by using a fullwave approach. The high convergence rate of the employed technique has allowed us to accurately and efficiently predict the filtering behavior of the considered structures. Results are presented for both TE and TM polarizations, showing the transmission efficiencies as a function of the involved parameters. In order to give more physical insight, a comparison with a simpler one-dimensional model has been provided. From our numerical investigation, it turns out that, by suitably configuring the photonic bandgap, it is possible to shape the filtering properties in TE polarization in a simple and versatile way.

$Research paper thumbnail of Characterization and design of two-dimensional electromagnetic band-gap structures by use of a full-wave method for diffraction gratings$

Characterization and design of two-dimensional electromagnetic band-gap structures by use of a full-wave method for diffraction gratings

IEEE Transactions on Microwave Theory and Techniques, 2003

In this paper, an accurate and efficient characterization of a two-dimensional (2-D) electromagne... more In this paper, an accurate and efficient characterization of a two-dimensional (2-D) electromagnetic band-gap (EBG) structures is performed, which exploits a full-wave diffraction theory developed for one-dimensional diffraction gratings. EBG materials constituted by 2-D arrays of dielectric rods with arbitrary shape and lattice configuration are analyzed, and the transmission and reflection efficiencies are determined. The high convergence rate of the proposed technique is demonstrated. Results are presented for both TE and TM polarizations, showing the efficiencies as a function of frequency and physical parameters. Comparisons with other theoretical results reported in the literature are shown with a very good agreement, and the authors' theory is also favorably compared with available experimental data. Useful design contour plots are reported by which a very immediate and accurate visualization of the band-gap configurations can be obtained, and design formulas are also included. Finally, the behavioral differences when a periodical defect is present are also highlighted.

Design and fabrication of a 3D-EBG superstrate for patch antennas

A layer-by-layer electromagnetic band-gap (EBG) structure has been fabricated by means of alumina... more A layer-by-layer electromagnetic band-gap (EBG) structure has been fabricated by means of alumina rods with square cross-section. The rods have been placed to form a woodpile structure; a square support with thin iron pins has been employed to obtain a precise rods alignment. The design parameters have been chosen to make the structure resonate at 11 GHz, when two identical woodpile layers are employed to form an EBG cavity. At the resonance, a unitary transmission occurs for an incident field, which can be employed in many microwave applications. In particular, a patch antenna has been fabricated to be used with the woodpile cavity, with properties of high directivity.

FMM and FDTD analysis of a woodpile 3D-EBG superstrate for patch antennas

Microwave and Optical Technology Letters, 2006

A fast and accurate modeling of the transmission and reflection properties of 3D-EBGs can be perf... more A fast and accurate modeling of the transmission and reflection properties of 3D-EBGs can be performed by exploiting a Fourier modal method (FMM), which in the literature is regarded as the most efficient and prevailing rigorous technique for the analysis of doubly-periodic gratings. Putting a woodpile EBG superstrate on a customary microstrip-patch feed, an antenna with highly directional radiation pattern can be obtained. The ensemble constituted by the perfectly conducting plane and the woodpile EBG can be schematized by means of an equivalent resonating all-dielectric structure, which has been studied by using our FMM tool for 3D-EBGs. Subsequently, the behavior of the whole radiating device has been checked with a finite difference time domain technique. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2595–2598, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21991

Full-Wave Characterization of Three-Dimensional Photonic Bandgap Structures

IEEE Transactions on Nanotechnology, 2006

In this paper, an accurate and efficient characterization of three-dimensional electromagnetic ba... more In this paper, an accurate and efficient characterization of three-dimensional electromagnetic bandgap (3D-EBG) structures is performed, which exploits a full-wave theory developed for doubly periodic gratings. The theoretical approach is presented, details on the numerical implementation are given, and the potentiality of the method in the analysis and design of EBGs is discussed. Convergence figures are reported and comparisons with both theoretical data available in the literature and in-house FDTD data are shown, with a very good agreement. Results are presented for EBGs with cubic inclusions, plots of the transmission efficiency as a function of geometrical and physical parameters are reported and commented on.

Fractal two-dimensional electromagnetic bandgap structures

IEEE Transactions on Microwave Theory and Techniques, 2004

Fractal two-dimensional electromagnetic bandgap (EBG) materials are proposed and studied by means... more Fractal two-dimensional electromagnetic bandgap (EBG) materials are proposed and studied by means of a full-wave method developed for diffraction gratings. Such technique allows us to characterize, in an accurate and rapidly convergent way, the transmission and reflection properties of periodic fractal structures with an arbitrary geometry in the unit cell. Both polarization cases can be treated. A validation of the employed method is performed through a comparison with theoretical results and experimental data taken from the literature; the convergence properties of our method when applied to fractal EBG materials are checked. In particular, three different fractal EBGs are considered here. Numerical results are reported for the transmission efficiency as a function of the frequency and the incidence angle. Typical effects due to the fractal geometry are observed, like multiband behavior and enlargement of stopbands.

Periodic defects in 2D-PBG materials: full-wave analysis and design

IEEE Transactions on Nanotechnology, 2003

In this paper, an accurate and efficient characterization of two-dimensional photonic bandgap str... more In this paper, an accurate and efficient characterization of two-dimensional photonic bandgap structures with periodic defects is performed, which exploits a full-wave diffraction theory developed for one-dimensional gratings. The high convergence rate of the proposed technique is demonstrated. Results are presented for both TE and TM polarizations, showing the efficiencies as a function of wavelength, incidence angle, geometrical and physical parameters. A comparison with other theoretical results reported in the literature is shown with a good agreement. The transmission properties of photonic crystals with periodic defects are studied, investigating the effects of the variation of geometrical and physical parameters; design efficiency maps and formulas are given; moreover, the application of the analyzed structures as filters is discussed.

Plane-wave expansion of cylindrical functions in lossy media

Optics Communications, 2006

Cylindrical waves, expressed as the product of a Hankel function of integer order times a sinusoi... more Cylindrical waves, expressed as the product of a Hankel function of integer order times a sinusoidal angular factor, are often employed in the solution of two-dimensional scattering problems. In this paper, a general closed-form expression for the angular spectrum of a cylindrical wave in a lossy medium is derived.

Scattering by Perfectly Conducting Circular Cylinders Buried in a Dielectric Slab Through the Cylindrical Wave Approach

IEEE Transactions on Antennas and Propagation, 2009

AbstractAn analytical-numerical technique for the solution of the plane-wave scattering problem ... more

Fast and accurate modeling of finite-thickness 2D-EBG structures made by circular-section rods

Microwave and Optical Technology Letters, 2003

In this paper, electromagnetic crystals constituted by 2D arrays of dielectric rods with a circul... more In this paper, electromagnetic crystals constituted by 2D arrays of dielectric rods with a circular cross section and rectangular-lattice configuration are analyzed, and the transmission and reflection efficiencies are determined. The high convergence rate of the proposed technique is demonstrated. Results are presented for both TE and TM polarizations, showing the efficiencies as a function of physical and geometrical parameters. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 433–437, 2003

A Spectral-Domain Solution for the Scattering Problem of aCircular Cylinder Buried in a Dielectric Half-Space

Progress in Electromagnetics Research-pier, 2002

A spectral-domain solution is employed to completely characterize the twodimensional electromagne... more A spectral-domain solution is employed to completely characterize the twodimensional electromagnetic plane-wave scattering problem by a perfectly conducting circular cylinder buried in a possibly lossy dielectric half-space. Use is made of the plane-wave spectrum to consider the di®raction, re°ection and transmission of cylindrical waves. Suitable adaptive integration techniques are employed to numerically solve the spectral integrals. The method is valid for any value of the cylinder radius, and of the distance between the cylinder and the interface.

Full-Wave Analysis of the Optimum Triplicator

Journal of Electromagnetic Waves and Applications, 2001

Starting from the results obtained in the scalar domain for the diffractive optical element that ... more Starting from the results obtained in the scalar domain for the diffractive optical element that produces three equi-intense diffraction orders with the maximum efficiency, we present a full-wave electromagnetic treatment of such optimum triplicator. The performances of this element are studied in the resonance domain and in the scalar limit as far as the dependence on the grating period, the

Scattering by buried dielectric cylindrical structures

Radio Science, 2005

1] An analytical-numerical technique for the solution of the two-dimensional electromagnetic plan... more 1] An analytical-numerical technique for the solution of the two-dimensional electromagnetic plane wave scattering by a finite set of dielectric circular cylinders buried in a dielectric half-space is presented. The problem is solved for both the near-and far-field regions, for transverse magnetic and transverse electric polarizations. The scattered field is represented in terms of a superposition of cylindrical waves, and use is made of the plane wave spectrum to take into account the reflection and transmission of such waves by the interface. The validity of the approach is confirmed by comparisons with results available in the literature, with very good agreement, and by self-consistency tests. Applications of the method to objects of arbitrary cross section simulated by suitable configurations of circular cylinders are shown. Citation: Di Vico, M., F. Frezza, L. Pajewski, and G. Schettini (2005), Scattering by buried dielectric cylindrical structures,

Scattering by a finite set of perfectly conducting cylinders buried in a dielectric half-space: a spectral-domain solution

IEEE Transactions on Antennas and Propagation, 2005

An analytical-numerical technique, for the solution of the two-dimensional electromagnetic plane-... more An analytical-numerical technique, for the solution of the two-dimensional electromagnetic plane-wave scattering by a finite set of perfectly conducting circular cylinders buried in a dielectric half-space, is presented. The problem is solved for both the near-and the far-field regions, for TM and TE polarizations. The diffracted field is represented in terms of a superposition of cylindrical waves and use is made of the plane-wave spectrum to take into account the reflection and transmission of such waves by the interface. The validity of the approach is confirmed by comparisons with results available in the literature, with very good agreement. The multiple interactions between two buried cylinders have been studied by considering both the induced currents and the scattered field diagrams. Applications of the method to objects of arbitrary cross-section simulated by a suitable configuration of circular cylinders are shown.

Design of a Binary Grating with Subwavelength Features that Acts as a Polarizing Beam Splitter

Applied Optics, 2001

A binary diffractive optical element, acting as a polarizing beam splitter, is proposed and analy... more A binary diffractive optical element, acting as a polarizing beam splitter, is proposed and analyzed. It behaves like a transmissive blazed grating, working on the first or the second diffraction order, depending on the polarization state of the incident radiation. The grating-phase profile required for both polarization states is obtained by means of suitably sized subwavelength groups etched in an isotropic dielectric medium. A rigorous electromagnetic analysis of the grating is presented, and numerical results concerning its performances in terms of diffraction efficiency as well as frequency and angular bandwidths are provided.

$Fig. 12. Average diffraction efficiencies of the transmitted orders TE, (filled circles) and TM, (open circles) plotted as functions of the maximum amplitude 6; of the random fabrication error for d, = 0.05d (M = 20).$

Modeling of three-dimensional electromagnetic band-gap structures

Cylindrical-wave approach for the electromagnetic scattering problem by buried two-dimensional objects

Journal of Applied Geophysics, 2009

The Cylindrical-Wave Approach (CWA) rigorously solves, in the spectral domain, the electromagneti... more The Cylindrical-Wave Approach (CWA) rigorously solves, in the spectral domain, the electromagnetic forward scattering by a finite set of buried two-dimensional perfectly-conducting or dielectric objects [1]- . In this technique, the field scattered by underground objects is represented in terms of a superposition of cylindrical waves. Use is made of the plane-wave spectrum [1] to take into account the interaction of such waves with the planar interface between air and soil, and between different layers eventually present in the ground.

Short-Pulse Electromagnetic Scattering by Buried Perfectly Conducting Cylinders

IEEE Geoscience and Remote Sensing Letters, 2007

In this letter, the electromagnetic scattering problem of a short-pulse plane wave by a finite se... more In this letter, the electromagnetic scattering problem of a short-pulse plane wave by a finite set of buried perfectly conducting circular cylinders is addressed in the time domain. The described procedure is applicable for arbitrary polarization and for any cylinder size and configuration in both near- and far-field regions. The solution is performed through an angular-spectrum representation of the scattered field. A parametric analysis on the effects of the various geometrical parameters is reported, and numerical results are presented.

FDTD Analysis of EBG Superstrates

Radiating devices, made up by woodpile electromagnetic bandgap (EBG) material superstrates placed... more Radiating devices, made up by woodpile electromagnetic bandgap (EBG) material superstrates placed over microstrip patches, are taken in consideration. Much interest is devoted to such antennas because of their enhanced directivity. The radiated far field has been calculated using an in- house finite-difference time-domain (FDTD) code. The microstrip position has been changed and the woodpile superstrate has been rotated: the

Application of a woodpile superstrate for directivity enhancement of antennas

Compel-the International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2008

Purpose – The purpose of this paper is to investigate the role of electromagnetic band-gap (EBG) ... more Purpose – The purpose of this paper is to investigate the role of electromagnetic band-gap (EBG) materials in the enhancement of antennas&amp;amp;amp;amp;amp;amp;#39; directivity. Design/methodology/approach – An analysis of a woodpile EBG material is performed, which points out its band properties. Woodpile cavities are then considered, obtained by interrupting the periodicity of the crystal. A woodpile cavity is then superimposed to