Ismael Barba

Publications

• Quasi-planar Chiral Materials for Microwave Frequencies

  Ismael Barba, A.C.L. Cabeceira, A.J. Garci?a-Collado, G.J. Molina-Cuberos, J. Margineda, J. Represa

  06/2011;

  ISBN: 978-953-307-445-0

• Chiral media based on periodic distribution of cranks. The four cranks resonator

  G.J. Molina-Cuberos, Á.J. García-Collado, I. Barba, A.C.L. Cabeceira, J. Represa, J. Margineda

  Fifth International Congress On Advanced Electromagnetic Materials In Microwaves And Optics (Metamaterials 2011), Barcelona (Spain); 01/2011

  A new structure consisting of four cranks, as the unit cell, to produce electromagnetic activity at microwave frequencies is proposed. A chiral medium is build by means of a 2D periodical distribution of the unit cell in printed circuit boards. By using a free-wave experimental setup, we have found ... [more] A new structure consisting of four cranks, as the unit cell, to produce electromagnetic activity at microwave frequencies is proposed. A chiral medium is build by means of a 2D periodical distribution of the unit cell in printed circuit boards. By using a free-wave experimental setup, we have found that the medium presents electromagnetic rotatory dispersion and circular dichroism at the X-band frequency range. The maximum on the rotation angle is observed at the end of the band with a magnitude of around 170 deg. Numerical studies confirm the experimental results and allow to study the phenomena in the Ku band, where another small resonance is found.

• Chiral Metamaterials with Negative Refractive Index Composed by an Eight-Cranks Molecule

  G. Molina-Cuberos, A. Garcia-Collado, J. Margineda, I. Barba

  IEEE Antennas and Wireless Propagation Letters. 01/2011; PP:1-3.

  A chiral medium constituted by a two-dimensional lattice of eight cranks of the same handedness is studied and found that it exhibits a huge electromagnetic activity, circular dichroism and negative refraction index. Using a free-wave experimental set up and numerical simulations, the transmission a... [more] A chiral medium constituted by a two-dimensional lattice of eight cranks of the same handedness is studied and found that it exhibits a huge electromagnetic activity, circular dichroism and negative refraction index. Using a free-wave experimental set up and numerical simulations, the transmission and reflection coefficients for a thin slab of such metamaterials were determined and the effective values for the refractive index, electric permittivity, magnetic permeability and chirality parameter were calculated. The obtained results by means of the simulation agree quite well with the ones calculated from the experimental measurements.

• Numerical study of electromagnetic wave propagation through layered structures with chiral media

  I. Barba, A. Gomez, A. C. L. Cabeceira, J. Represa, A. Vegas, M. A. Solano

  International Journal of Numerical Modelling-Electronic Networks Devices and Fields. 01/2010; 23(6):411-424.

  In this paper, the characteristics of layered structures (photonic or electromagnetic bandgaps), including chiral media, are studied by means of two different numerical methods, one in the time domain (finite differences in the time domain, FDTD) and the other in the frequency domain (coupled-mode m... [more] In this paper, the characteristics of layered structures (photonic or electromagnetic bandgaps), including chiral media, are studied by means of two different numerical methods, one in the time domain (finite differences in the time domain, FDTD) and the other in the frequency domain (coupled-mode method, CMM). The results (reflection and transmission coefficients for a plane wave normally incident over a layered structure) obtained by means of both well different techniques are practically identical. Copyright (C) 2009 John Wiley & Sons, Ltd.

• Chiral Media Based on Printed-Circuit Board Technology: A Numerical Time-Domain Approach

  I. Barba, A. C. L. Cabeceira, A. Gomez, J. Represa

  Ieee Transactions on Magnetics. 01/2009; 45(3):1170-1173.

  The common design of artificial chiral media for microwave frequencies is based on the inclusion of particles with chiral symmetry (i.e., specular symmetry or handedness) into a host medium. Recently, we have considered new fabrication techniques based on printed-circuit board technology, because th... [more] The common design of artificial chiral media for microwave frequencies is based on the inclusion of particles with chiral symmetry (i.e., specular symmetry or handedness) into a host medium. Recently, we have considered new fabrication techniques based on printed-circuit board technology, because the use of via holes gives us great additional flexibility to select the type of chiral inclusions from helix to cranks. In this paper, a numerical study in the time domain of the electromagnetic-wave propagation through these types of structures is achieved by using the commercial software MEFiSTo, a time-domain electromagnetic simulator based on the transmission-line matrix method.

• Application of Schelkunoff's method for simulating isotropic chiral free propagation: Clarifying some common errors

  A. Gomez, I. Barba, A. C. L. Cabeceira, J. Represa, A. Vegas, M. A. Solano

  Journal of Electromagnetic Waves and Applications. 01/2008; 22(5-6):861-871.

  Schelkunoff's method, also commonly refered to as Coupled Mode Method (CMM), is a numerical method which gives the propagation constants and the electromagnetic field in a general homogeneous medium bounded by perfect electric walls. In this paper, we test Schelkunoff's method for a waveguid... [more] Schelkunoff's method, also commonly refered to as Coupled Mode Method (CMM), is a numerical method which gives the propagation constants and the electromagnetic field in a general homogeneous medium bounded by perfect electric walls. In this paper, we test Schelkunoff's method for a waveguide filled with an isotropic chiral material (chirowaveguide) where the dimensions of the walls are electrically large compared with the wavelength. It is reasonable to foresee that, in this case, the results given by Schelkunoff's method must approach to the corresponding ones for the chiral unbounded medium. Effectively, we obtain the solutions for both circular polarized waves (right-handed and left-handed) in free propagation in a single calculation. These results are in opposition with those of other authors analyzing analogous cases.

• Electromagnetic propagation in unbounded inhomogeneous chiral media using the coupled mode method (vol 49, pg 2771, 2007)

  A. Gomez, I. Barba, A. C. L. Cabeceira, J. Represa, A. Vegas, A. Grande, M. A. Solano

  Microwave and Optical Technology Letters. 01/2008; 50(4):1132-1132.

• Electromagnetic propagation in unbounded inhomogeneous chiral media using the coupled mode method

  A. Gomez, I. Barba, A. C. L. Cabeceira, J. Represa, A. Vegas, M. A. Solano

  Microwave and Optical Technology Letters. 01/2007; 49(11):2771-2779.

  The coupled mode method (CMM) is a seminumerical method for studying electromagnetic propagation, originally formulated for closed structures. We show how this method can be used,for obtaining the propagation constants and electromagnetic field in unbounded isotropic chiral media. We also characteri... [more] The coupled mode method (CMM) is a seminumerical method for studying electromagnetic propagation, originally formulated for closed structures. We show how this method can be used,for obtaining the propagation constants and electromagnetic field in unbounded isotropic chiral media. We also characterize single and periodic cascade discontinuities made of isotropic chiral slabs by means of the mode matching method combined with the CMM. The results or(, tested with a robust FDTD technique, modified to model bi-isotropic media and with analytical solutions. In all cases good agreement is found. (D 2007 Wiley Periodicals, Inc.
• 2.01

  Impact points

  A Multiresolution Model of Transient Microwave Signals in Dispersive Chiral Media

  I. Barba, A. Grande, A.C.L. Cabeceira, J. Represa

  Antennas and Propagation, IEEE Transactions on. 11/2006;

  A multiresolution in time domain method is used to model the propagation of transient signals through dispersive chiral media. The modeling of these media requires the computation of convolution integrals, whose resolution level may be increased by introducing wavelets in the time dependence of the ... [more] A multiresolution in time domain method is used to model the propagation of transient signals through dispersive chiral media. The modeling of these media requires the computation of convolution integrals, whose resolution level may be increased by introducing wavelets in the time dependence of the fields
• 2.08

  Impact points

  A time-domain modeling for EM wave propagation in bi-isotropic media based on the TLM method

  A.C.L. Cabeceira, A. Grande, I. Barba, J. Represa

  Microwave Theory and Techniques, IEEE Transactions on. 07/2006;

  A transmission-line matrix model suitable to model the propagation of electromagnetic (EM) waves in bi-isotropic media is presented. The main characteristic of the EM response of such complex media is the cross coupling of the EM field vectors in their constitutive relations. In this study, the angl... [more] A transmission-line matrix model suitable to model the propagation of electromagnetic (EM) waves in bi-isotropic media is presented. The main characteristic of the EM response of such complex media is the cross coupling of the EM field vectors in their constitutive relations. In this study, the angle tilt between electric and magnetic field vectors, the intrinsic impedances, the effective parameters of the medium, and the rotation of the polarization plane are computed. The results are in very good agreement with the theoretical solution

• 2D-TLM model for propagation in biisotropic media

  A.C.L. Cabeceira, A. Grande, I. Barba, J. Represa

  Microwave Conference, 2005 European; 11/2005

  A TLM model suitable to model the propagation of electromagnetic waves in biisotropic media is presented. The main characteristic of the electromagnetic response of such complex media is the cross coupling of the electromagnetic field vectors in its constitutive relationships. In this work, the angl... [more] A TLM model suitable to model the propagation of electromagnetic waves in biisotropic media is presented. The main characteristic of the electromagnetic response of such complex media is the cross coupling of the electromagnetic field vectors in its constitutive relationships. In this work, the angle tilt between electric and magnetic field vectors, the intrinsic impedances, the effective parameters of the medium, and the rotation of the polarization plane are computed. The results for a monochromatic source are in very good agreement with the theoretical solution.

• Study on the stability of the FDTD extension for modeling transient propagation in dispersive bi-isotropic media

  A. Grande, I. Barba, A.C. Cabeceira, J. Represa, O. Gonzalez, J.A. Pereda

  Antennas and Propagation Society International Symposium, 2005 IEEE; 08/2005

  This paper addresses the problem of the stability analysis and the numerical dispersion of a recently developed extension of the conventional FDTD scheme to incorporate bi-isotropic media. This FDTD formulation developed is a second order accurate conditionally stable algorithm that allows computing... [more] This paper addresses the problem of the stability analysis and the numerical dispersion of a recently developed extension of the conventional FDTD scheme to incorporate bi-isotropic media. This FDTD formulation developed is a second order accurate conditionally stable algorithm that allows computing transient wave propagation in general dispersive lossy bi-isotropic media. The von Neumann technique is applied to compute the associated characteristic polynomial. The stability condition is that all the roots of this polynomial have modulus less than or equal to unity. For full bi-isotropic media the roots have to be numerically computed as a function of the medium and simulation parameters. The dispersion relation for a dispersive bi-isotropic medium is derived.
• 1.91

  Impact points

  Two-dimensional extension of a novel FDTD technique for modeling dispersive lossy bi-isotropic media using the auxiliary differential equation method

  A. Grande, I. Barba, A.C.L. Cabeceira, J. Represa, K. Karkkainen, A.H. Sihvola

  Microwave and Wireless Components Letters, IEEE. 06/2005;

  This letter describes a two-dimensional (2-D) extension of a recently developed finite-difference time-domain (FDTD) scheme to model wave propagation in bi-isotropic media. To our knowledge this method is the only one successfully generalized to modeling transient microwave signals in general lossy ... [more] This letter describes a two-dimensional (2-D) extension of a recently developed finite-difference time-domain (FDTD) scheme to model wave propagation in bi-isotropic media. To our knowledge this method is the only one successfully generalized to modeling transient microwave signals in general lossy dispersive bi-isotropic media. The new 2-D cell built and computational procedure of the FDTD algorithm developed is described. Condon and Lorentz dispersion models have been included for modeling the frequency dependence of the medium parameters and the auxiliary differential equation (ADE) method is considered to deal with dispersion in order to avoid defining complex back-stored numbers to compute the convolutions recursively. Finally the oblique incidence of a wave on a chiral medium and the propagation in a general lossy bi-isotropic medium have been successfully simulated.

• PML absorbing boundary conditions for the multiresolution time-domain techniques based on the discrete wavelet transform

  C. Represa, C. Pereira, A. C. L. Cabeceira, I. Barba, J. Represa

  Applied Computational Electromagnetics Society Journal. 01/2005; 20(3):207-212.

  The use of numerical methods to solve electromagnetic problems with open boundaries requires a method to limit the domain in which the field is computed. This can be achieved by truncating the mesh and setting certain numerical boundary conditions on the outer perimeter of the domain to simulate its... [more] The use of numerical methods to solve electromagnetic problems with open boundaries requires a method to limit the domain in which the field is computed. This can be achieved by truncating the mesh and setting certain numerical boundary conditions on the outer perimeter of the domain to simulate its extension to infinity. In this paper, the formulation of the perfectly matched layer (PML) is applied to the multiresolution time-domain technique (MRTD) to effectively simulate free-space. The PML region is modelled by means of the two-dimensional discrete wavelet transform. In addition, the numerical reflectivity of the PML medium is also investigated for a variety of thicknesses.

• Advances in time domain numerical modeling for electromagnetic wave propagation in bi-isotropic media

  A. Grande, A.C.L. Cabeceira, I. Barba, J. Represa

  Physics and Engineering of Microwaves, Millimeter, and Submillimeter Waves, 2004. MSMW 04. The Fifth International Kharkov Symposium on; 07/2004

  In this paper, the recent advances in extending the traditional time-domain techniques have been discussed. The main objective of this work is to model the electromagnetic wave propagation in general bi-isotopic media using advanced time-domain numerical modeling such as Finite Differences in Time D... [more] In this paper, the recent advances in extending the traditional time-domain techniques have been discussed. The main objective of this work is to model the electromagnetic wave propagation in general bi-isotopic media using advanced time-domain numerical modeling such as Finite Differences in Time Domain (FDTD) and Transmission Line Matrix (TLM).

• A 2D-TLM model for electromagnetic wave propagation in chiral media

  A.C.L. Cabeceira, A. Grande, I. Barba, J. Represa

  Antennas and Propagation Society International Symposium, 2004. IEEE; 07/2004

  A TLM model suitable to simulate the propagation of electromagnetic waves in bi-isotropic media is presented. One of the main characteristics of the electromagnetic response of such complex media is the rotation of the polarization plane. The obtained results for a monochromatic source are in very g... [more] A TLM model suitable to simulate the propagation of electromagnetic waves in bi-isotropic media is presented. One of the main characteristics of the electromagnetic response of such complex media is the rotation of the polarization plane. The obtained results for a monochromatic source are in very good agreement with the theoretical solution.
• 2.08

  Impact points

  FDTD modeling of transient microwave signals in dispersive and lossy bi-isotropic media

  A. Grande, I. Barba, A.C.L. Cabeceira, J. Represa, P.P.M. So, W.J.R. Hoefer

  Microwave Theory and Techniques, IEEE Transactions on. 04/2004;

  In this paper, we present a novel finite-difference time-domain model of transient wave propagation in general dispersive bi-isotropic media with losses. The special properties of these materials may lead to new applications in microwave and millimeter-wave technology. While their frequency-domain p... [more] In this paper, we present a novel finite-difference time-domain model of transient wave propagation in general dispersive bi-isotropic media with losses. The special properties of these materials may lead to new applications in microwave and millimeter-wave technology. While their frequency-domain properties have been well described in the literature, their time-domain behavior has only been modeled thus far for special sub-classes and monochromatic time dependence. We have validated our method by first computing time-harmonic wave propagation through a bi-isotropic medium and comparing it with analytical results. Agreement is typically better than 1%. We have then computed transient field propagation in a general lossy dispersive bi-isotropic medium.
• 2.01

  Impact points

  Comments on the far zone scattering calculation of frequency-dependent materials objects using TLM method

  J. Represa, I. Barba, A.C.L. Cabeceira

  Antennas and Propagation, IEEE Transactions on. 02/2004;

  No abstract available.

• A 2D-TLM model for electromagnetic wave propagation in tellegen media

  A. C. L. Cabeceira, I. Barba, A. Grande, J. Represa

  Microwave and Optical Technology Letters. 01/2004; 40(5):438-441.

  A TLM model suitable to simulate the propagation of electromagnetic waves in Tellegen media is presented. The angle tilt between electromagnetic field vectors, the intrinsic impedances and the effective parameters of the medium are computed. The results for a monochromatic source are in very good ag... [more] A TLM model suitable to simulate the propagation of electromagnetic waves in Tellegen media is presented. The angle tilt between electromagnetic field vectors, the intrinsic impedances and the effective parameters of the medium are computed. The results for a monochromatic source are in very good agreement with the analytical solution. (C) 2004 Wiley Periodicals, Inc.

• Advances in time domainnumerical modeling for electromagnetic-wave tropagation in bi-isotropic media

  A. Grande, A. C. L. Cabeceira, I. Barba, J. Represa

  Msmw'04: Fifth International Kharkov Symposium on Physics and Engineering of Microwaves, Millimeter, and Submillimeter Waves, Symposium Proceedings, Vols 1 and 2. 01/2004;