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Rodríguez Ulibarri, Pablo

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Rodríguez Ulibarri

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Pablo

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0000-0001-5705-5457

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2011 - 202023
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Now showing 1 - 10 of 23
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    PublicationOpen Access
    Nonbianisotropic complementary split ring resonators as angular selective metasurfaces
    (Optical Society of America, 2017) Rodríguez Ulibarri, Pablo; Beruete Díaz, Miguel; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
    In this work, a metasurface with unconventional angular performance and composed by a nonbianisotropic complementary split ring resonator (NB-CSRR) is analyzed numerically and experimentally. A numerical study comparing the performance with the original complementary split ring resonator is conducted, showing very interesting transmission properties, such as complete filtering under normal incidence and high transmission peaks at oblique incidence for the NB-CSRR metasurface. A bilayered NB-CSRR prototype working at millimeter waves with a total thickness of 100 μm (0.1 times the operation wavelength) is fabricated and tested with a good agreement between simulation results and experiments. Very exciting applications based on the presented structure, such as advanced angular selectivity devices with great rejection levels at normal incidence and angular sensing devices, can be envisaged.
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    PublicationOpen Access
    Annular apertures in metallic screens as extraordinary transmission and frequency selective surface structures
    (IEEE, 2017) Rodríguez Ulibarri, Pablo; Navarro Cía, Miguel; Rodríguez Berral, Raúl; Mesa, Francisco; Medina, Francisco; Beruete Díaz, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    A 2-D periodic array of annular apertures (or ring slots) is studied using an accurate circuit model. The model accounts for distributed and dynamic effects associated with the excitation of high-order modes operating above or below cutoff but not far from their cutoff frequencies. This paper allows to ascertain the substantial differences of the underlying physics when this structure operates as a classical frequency selective surface or in the extraordinary-transmission (ET) regime. A discussion of two different designs working at each regime is provided by means of the equivalent circuit approach (ECA), full wave simulation results, and experimental characterization. The agreement between the equivalent circuit calculation applied here and the simulation and experimental results is very good in all the considered cases. This validates the ECA as an efficient minimal-order model and a low computational-cost design tool for frequency selective surfaces and ET-based devices. Additional scenarios such as oblique incidence and parametric studies of the structural geometry are also considered.
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    PublicationOpen Access
    One-way quasiplanar terahertz absorbers using nonstructured polar dielectric layers
    (American Physical Society, 2017) Rodríguez Ulibarri, Pablo; Serebryannikov, Andriy E.; Beruete Díaz, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    A concept of quasiplanar one-way transparent terahertz absorbers made of linear isotropic materials is presented. The resulting structure consists of a homogeneous absorbing layer of polar dielectric, GaAs, a dispersion-free substrate, and an ultrathin frequency-selective reflector. It is demonstrated that perfect absorption can be obtained for forward illumination, along with total reflection at backward illumination and transparency windows in the adjacent bands. The design is particularized for the polaritonic gap range where permittivity of GaAs varies in a wide range and includes epsilon-near-zero and transparency regimes. The underlying physics can be explained with the aid of a unified equivalent-circuit (EC) analytical model. Perfect matching of input impedance in forward operation and, simultaneously, strong mismatch in the backward case are the universal criteria of one-way absorption. It is shown that perfect one-way absorption can be achieved at rather arbitrary permittivity values, provided these criteria are fulfilled. The EC results are in good agreement with full-wave simulations in a wide range of material and geometrical parameters. The resulting one-way absorbers are very compact and geometrically simple, and enable transparency in the neighboring frequency ranges and, hence, multifunctionality that utilizes both absorption- and transmission-related regimes.
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    PublicationOpen Access
    Wide angle terahertz sensing with a cross-dipole frequency selective surface
    (AIP Publishing, 2016) Rodríguez Ulibarri, Pablo; Kuznetsov, Sergei A.; Beruete Díaz, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    In this work, a terahertz sensor based on a cross dipole frequency selective surface is analyzed and experimentally tested. The sensing structure is optimized for operation at the fundamental band- stop resonance near 0.7THz and characterized under normal and oblique incidence. The sensing performance as a function of the incidence angle and the wave polarization is evaluated with good agreement between simulations and measurements. It is shown that a figure of merit for the pro- posed sensor can be enhanced from 0.2 up to 0.6 due to switching from normal to oblique excita- tion, which yields the maximum performance for TM polarization at the incidence angle of 70º. The presented results demonstrate a wide angle operation regime in THz sensing that opens up an alternative approach in improving capabilities of sensing devices.
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    PublicationOpen Access
    On the performance of an ENZ-based sensor using transmission line theory and effective medium approach
    (IOP Publishing, 2019) Pacheco-Peña, Víctor; Beruete Díaz, Miguel; Rodríguez Ulibarri, Pablo; Engheta, Nader; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Eléctrica, Electrónica y de Comunicación
    In this paper we perform an in-depth theoretical studyofa sensing platform based on epsilon-near- zero (ENZ) metamaterials. The structure proposed for sensing is a narrow metallic waveguide channel. An equivalent circuit model is rigorouslydeduced using transmission line theory, considering several configurations for a dielectric body (analyte sample) inserted within the narrow channel, showing good agreement with results obtained from numerical simulations. The transmission line model is able to reproduce even the most peculiar details ofthe sensing platform response. Its performance is then evaluated byvarying systematically the size, position and permittivity ofthe analyte, and height ofthe ENZ channel. It is shown that the sensor is capable ofdetecting changes in the permittivity/ refractive index or position even with deeplysubwavelength analyte sizes (∼0.05λ0), giving a sensitivity up to 0.03m/RIU and a figure ofMerit∼25. The effective medium approach is evaluated by treating the inhomogeneous cross-section ofthe analyte as a transmission line filled with a homogeneous material.
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    PublicationOpen Access
    Analysis of antenna transient radiation
    (2011) Rodríguez Ulibarri, Pablo; Gómez Laso, Miguel Ángel; Yarovoy, Alexander; Caratelli, Diego; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Delft University of Technology (Holanda); Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    Recently a new formalism has been developed for modeling time domain radiation processes in complex antennas. Using this formalism the radiated electromagnetic field can be expressed in terms of non uniform spherical wave contributions relevant to the resonant phenomena occurring in the structure. The developed algorithm consists of a dedicated two-step vector fitting procedure. Firstly, the spherical harmonic expansion of the time-domain equivalent electric and magnetic currents is performed. Then, by using the Singularity-Expansion-Method (SEM), the time-variant spherical harmonic expansion coefficients are represented in terms of dumped exponential terms. In this way, by using the incomplete modified spherical Bessel functions, an analytical description of the transient wave radiation phenomena is achieved. In this study several canonical radiating structures such as dipole, bow-tie and loop antennas, have been analyzed using the afore-mentioned formalism in order to gain a physical insight into the natural resonant processes occurring in the antenna and find a relation with the relevant geometrical characteristics.
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    PublicationOpen Access
    THz sensing with anomalous extraordinary optical transmission hole arrays
    (MDPI, 2018) Jáuregui López, Irati; Rodríguez Ulibarri, Pablo; Kuznetsov, Sergei A.; Nikolaev, Nazar A.; Beruete Díaz, Miguel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
    Subwavelength hole array (HA) metasurfaces support the so-called extraordinary optical transmission (EOT) resonance that has already been exploited for sensing. In this work, we demonstrate the superior performance of a different resonant regime of HA metasurfaces called anomalous EOT, by doing a thorough numerical and experimental study of its ability in thin-film label-free sensing applications in the terahertz (THz) band. A comprehensive analysis using both the regular and anomalous EOT resonances is done by depositing thin layers of dielectric analyte slabs of different thicknesses on the structures in different scenarios. We carry out a detailed comparison and demonstrate that the best sensing performance is achieved when the structure operates in the anomalous EOT resonance and the analyte is deposited on the non-patterned side of the metasurface, improving by a factor between 2 and 3 the results of the EOT resonance in any of the considered scenarios. This can be explained by the comparatively narrower linewidth of the anomalous EOT resonance. The results presented expand the reach of subwavelength HAs for sensing applications by considering the anomalous EOT regime that is usually overlooked in the literature.
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    PublicationOpen Access
    Metamaterials and extraordinary transmission structures applied to microwave, millimeter and terahertz waves devices
    (2017) Rodríguez Ulibarri, Pablo; Beruete Díaz, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    Los metamateriales aparecen en los primeros años del siglo XXI como materiales artificiales que presentan un comportamiento electromagnético de alguna manera exótico. Al mismo tiempo, se descubre un nuevo fenómeno denominado transmisión extraordinaria. Ambas disciplinas conllevaron a una revisión profunda del electromagnetismo básico aunando dos comunidades científicas que últimamente permanecían desligadas, las microondas y la óptica. Además, tanto los metamateriales como la transmisión extraordinaria fueron explotados para desarrollar nuevos dispositivos para un amplio abanico de aplicaciones tales como seguridad, comunicaciones o espectroscopía. En esta Tesis se investiga el uso de dispositivos inspirados en estructuras metamaterial y el fenómeno de transmisión extraordinaria operando a frecuencias de microondas, ondas milimétricas y terahercios. El contenido de la Tesis se puede dividir en tres partes diferenciadas que se relacionan con cada uno de los rangos frecuenciales estudiados, es decir, microondas, ondas milimétricas y terahercios. La primera parte de la Tesis está dedicada a investigar cómo los metamateriales pueden mejorar las prestaciones de un sistema de antenas para aplicaciones radar en el rango de las microondas. La segunda parte trata de forma teórica y experimental diferentes estructuras periódicas bidimensionales que trabajan en el rango de las ondas milimétricas con el fin de estudiar los límites entre el fenómeno de transmisión extraordinaria y regímenes ordinarios, diseñar dispositivos unidireccionales y sintonizables y metasuperficies con una respuesta angular no convencional. Finalmente, la tercera parte de la Tesis, hace extensible el uso de estructuras periódicas bidimensionales para aplicaciones de sensado a frecuencias de terahercio.
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    PublicationOpen Access
    Mid-infrared spectroscopy (MIR) for simultaneous determination of fat and protein content in meat of several animal species
    (Springer, 2017) Lozano Saiz, María; Rodríguez Ulibarri, Pablo; Echeverría Morrás, Jesús; Beruete Díaz, Miguel; Sorolla Ayza, Mario; Beriain Apesteguía, María José; Institute of Smart Cities - ISC; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Institute for Advanced Materials and Mathematics - INAMAT2
    The aim of this research was to study the application of MIR spectroscopy as an alternative to conventional methods to determine fat and protein content. Samples of the main species used to produce meat products were analyzed, showing all of them absorption bands at similar wavenumbers though with different intensity. Correlation analysis of absorption intensities showed that bands around 2925, 2854, and 1746 cm−1 are associated with fat content, whereas bands around 3288, 1657, and 1542 cm−1 are associated with proteins. During the validation process, prediction models of fat and protein content were successfully obtained withR2 0.9173 and 0.7534, respectively. Finally, a good result (R2 =0.8829) was obtained on the estimation of the lipid content when the information at only one wavenumber was used.
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    PublicationOpen Access
    Low profile THz periodic leaky-wave antenna
    (IEEE, 2014) Beaskoetxea Gartzia, Unai; Beruete Díaz, Miguel; Rodríguez Ulibarri, Pablo; Etayo Salinas, David; Sorolla Ayza, Mario; Navarro Cía, Miguel; Zehar, Mokhtar; Blary, Karine; Chahadih, Abdallah; Han, Xiang-Lei; Akalin, Tahsin; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    In this work, a 0.566THz flat leaky-wave antenna, consisting of a central λ0/2 slot surrounded by straight parallel wedge corrugations, is numerically and experimentally analyzed. Simulations show a moderately high gain and no significant differences when compared with a typical square corrugation profile. Numerical comparison is also made for the designed and manufactured antennas. High transmission enhancement in the corrugated case is obtained, compared to that given by a single central slot with no grooves. This kind of antennas finds several applications in different frequency ranges, including the nowadays high-interest range of the THz.