• Compact dual-band terahertz quarter-wave plate metasurface 

      Torres Landívar, Víctor Upna; Etayo Salinas, David Upna; Ortuño Molinero, Rubén Upna; Navarro Cía, Miguel Upna Orcid; Beruete Díaz, Miguel Upna Orcid (IEEE, 2014)   Artículo / Artikulua  OpenAccess
      A dual-band quarter-wave plate based on a modified extraordinary transmission hole array is numerically analyzed and experimentally demonstrated at terahertz frequencies. To control independently orthogonal polarizations, ...
    • Compact ultra wide band microstrip bandpass filter based on multiple-mode resonator and modified complementary split ring resonator 

      Marcotegui, José Antonio Upna; Illescas, Jesús; Estévez González, Aritz; Falcone Lanas, Francisco Javier Upna Orcid (Hindawi, 2013)   Artículo / Artikulua  OpenAccess
      A new class of broadband microstrip filters for Ultra Wide Band (UWB) applications is proposed. In the design, different stages of parallel-coupled microstrip line and other stages with a Modified Complementary Split Ring ...
    • A comparative study in the sensitivity of optical fiber refractometers based on the incorporation of gold nanoparticles into layer-by-layer films 

      Rivero Fuente, Pedro J. Upna Orcid; Hernáez Sáenz de Zaitigui, Miguel Upna Orcid; Goicoechea Fernández, Javier Upna Orcid; Matías Maestro, Ignacio Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid (Exeley, 2015)   Artículo / Artikulua  OpenAccess
      In this work, optical fiber refractometers based on the successive incorporation of gold nanoparticles have been fabricated by means of the Layer-by-Layer Embedding (LbL-E) deposition technique. This enables the apparition ...
    • Comparative study of layer-by-layer deposition techniques for poly(sodium phosphate) and poly (allylamine hydrochloride) 

      Elosúa Aguado, César Upna Orcid; López Torres, Diego Upna Orcid; Hernáez Sáenz de Zaitigui, Miguel Upna Orcid; Matías Maestro, Ignacio Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid (Springer, 2013)   Artículo / Artikulua  OpenAccess
      An inorganic short chain polymer, poly(sodium phosphate), PSP, together with poly(allylamine hydrochloride), PAH, is used to fabricate layer-by-layer (LbL) films. The thickness, roughness, contact angle, and optical ...
    • Comparative study of ring and random cavities for fiber lasers 

      Fernández Vallejo, Montserrat Upna; Rota Rodrigo, Sergio Upna; López-Amo Sáinz, Manuel Upna Orcid (Optical Society of America, 2014)   Artículo / Artikulua  OpenAccess
      An experimental comparison of three fiber laser structures with the same Raman gain medium is presented in order to establish the main pros and cons of each basic scheme. The first fiber laser is based on a hybrid ring–random ...
    • A comparative study of two different approaches for the incorporation of silver nanoparticles into layer-by-layer films 

      Rivero Fuente, Pedro J. Upna Orcid; Goicoechea Fernández, Javier Upna Orcid; Matías Maestro, Ignacio Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid (Springer, 2014)   Artículo / Artikulua  OpenAccess
      In this work, a comparative study about the incorporation of silver nanoparticles (AgNPs) into thin films is presented using two alternative methods, the in situ synthesis process and the layer-by-layer embedding deposition ...
    • Comparison between capacitive and microstructured optical fiber soil moisture sensors 

      López Aldaba, Aitor Upna; López Torres, Diego Upna Orcid; Campo-Bescós, Miguel Upna Orcid; López Rodríguez, José Javier Upna Orcid; Yerro Lizarazu, David; Elosúa Aguado, César Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel Upna Orcid (MDPI, 2018)   Artículo / Artikulua  OpenAccess
      Soil moisture content has always been an important parameter to control because it is a deterministic factor for site-specific irrigation, seeding, transplanting, and compaction detection. In this work, a discrete sensor ...
    • Comparison of wavelength-division-multiplexed distributed fiber Raman amplifier networks for sensors 

      Díaz Lucas, Silvia Upna Orcid; López-Amo Sáinz, Manuel Upna Orcid (Optical Society of America, 2006)   Artículo / Artikulua  OpenAccess
      A novel distributed fiber Raman amplified star topology used for optical sensor wavelength-division multiplexing is proposed. The performance of this star configuration is compared to an optically amplified bus topology. ...
    • Compound lasing fiber optic ring resonators for sensor sensitivity enhancement 

      Rota Rodrigo, Sergio Upna; González Herráez, Miguel; López-Amo Sáinz, Manuel Upna Orcid (IEEE / OSA, 2015)   Artículo / Artikulua  OpenAccess
      In this work, a new method for increasing simultaneously the sensitivity and interrogation stability of fiberoptic intensity sensors is presented. The configuration is based on a double-coupler ring resonator. On one side, ...
    • A comprehensive analysis of the absorption spectrum of conducting ferromagnetic wires 

      Liberal Olleta, Íñigo Upna Orcid; Ederra Urzainqui, Íñigo Upna Orcid; Gómez Polo, Cristina Upna Orcid; Labrador Otamendi, Alberto; Pérez de Landazábal Berganzo, José Ignacio Upna Orcid; Gonzalo García, Ramón Upna Orcid (IEEE, 2012)   Artículo / Artikulua  OpenAccess
      A detailed analysis of the absorption spectrum of conductive ferromagnetic wires is presented. The absorption spectrum is computed from the solution to the scattering problem, and circuit models are formulated to clarify ...
    • A comprehensive model for lithium-ion batteries: from the physical principles to an electrical model 

      Berrueta Irigoyen, Alberto Upna Orcid; Urtasun Erburu, Andoni Upna Orcid; Ursúa Rubio, Alfredo Upna Orcid; Sanchis Gúrpide, Pablo Upna Orcid (Elsevier, 2018)   Artículo / Artikulua  OpenAccess
      The growing interest in e-mobility and the increasing installation of renewable energy-based systems are leading to rapid improvements in lithium-ion batteries. In this context, battery manufacturers and engineers require ...
    • Concrete beam bending test monitorization using a high strain fiber optic sensor 

      Bravo Acha, Mikel Upna Orcid; Sáenz, J.; Bravo Navas, M.; López-Amo Sáinz, Manuel Upna Orcid (IEEE / OSA, 2012)   Artículo / Artikulua  OpenAccess
      In this work the development of an 'eight-shape' fiber optic sensor for high strain measurement is experimentally demonstrated. This strain sensor is interrogated using a commercial optical time domain reflectometer through ...
    • Consistent modeling and power gain analysis of microwave SiGe HBTs in CE and CB configurations 

      Álvarez Botero, Germán Andrés; Torres-Torres, Reydezel; Murphy-Arteaga, Roberto S. (IEEE, 2015)   Artículo / Artikulua  OpenAccess
      This paper presents a methodology to model SiGe HBTs biased in common-emitter and in common-base configurations including the bias-dependent substrate parasitics, which allows determining the more suitable configuration ...
    • Continuous liquid-level sensor based on a long-period grating and microwave photonics filtering techniques 

      Ricchiuti, Amelia L.; Barrera, D.; Urrutia Azcona, Aitor Upna Orcid; Goicoechea Fernández, Javier Upna Orcid; Arregui San Martín, Francisco Javier Upna Orcid (IEEE, 2016)   Artículo / Artikulua  OpenAccess
      A fiber optic liquid-level sensor based on a long period grating (LPG) is proposed and experimentally validated. The principle of operation is based on a technique used to analyze microwave photonics filters. A 4-cm-long ...
    • Control of a single-switch two-input buck converter for MPPT of two PV strings 

      Urtasun Erburu, Andoni Upna Orcid; Dah-Chuan Lu, Dylan (IEEE, 2015)   Artículo / Artikulua  OpenAccess
      In this paper, the Two-Input Buck (TIBuck) converter is proposed as the DC/DC stage for photovoltaic (PV) cascaded converters. This converter is attractive for this application because it is cost-effective and reliable and ...
    • Control strategies to smooth short-term power fluctuations in large photovoltaic plants using battery storage systems 

      Marcos Álvarez, Javier Upna Orcid; Parra Laita, Íñigo de la Upna Orcid; García Solano, Miguel Upna Orcid; Marroyo Palomo, Luis Upna Orcid (MDPI, 2014)   Artículo / Artikulua  OpenAccess
      The variations in irradiance produced by changes in cloud cover can cause rapid fluctuations in the power generated by large photovoltaic (PV) plants. As the PV power share in the grid increases, such fluctuations may ...
    • Converging biconcave metallic lens by double-negative extraordinary transmission metamaterial 

      Navarro Cía, Miguel Upna Orcid; Beruete Díaz, Miguel Upna Orcid; Sorolla Ayza, Mario Upna; Campillo, Igor (AIP Publishing, 2009)   Artículo / Artikulua  OpenAccess
      In this letter we present simulation and experimental results of a left-handed converging biconcave metallic lens made of stacked subwavelength hole arrays SSHAs working in the millimeter wave range with additional ...
    • Correlation between discharge timings of pairs of motor units reveals the presence but not the proportion of common synaptic input to motor neurons 

      Rodríguez Falces, Javier Upna Orcid; Negro, Francesco; Farina, Dario (American Physiological Society, 2017)   Artículo / Artikulua  OpenAccess
      We investigated whether correlation measures derived from pairs of motor unit (MU) spike trains are reliable indicators of the degree of common synaptic input to motor neurons. Several 50-s isometric contractions of the ...
    • Cost-effective Brillouin optical time-domain analysis sensor using a single optical source and passive optical filtering 

      Iribas Pardo, Haritz Upna Orcid; Urricelqui Polvorinos, Javier Upna Orcid; Mariñelarena Ollacarizqueta, Jon Upna Orcid; Sagüés García, Mikel Upna Orcid; Loayssa Lara, Alayn Upna Orcid (Hindawi Publishing Corporation, 2016)   Artículo / Artikulua  OpenAccess
      We present a simplified configuration for distributed Brillouin optical time-domain analysis sensors that aims to reduce the cost of the sensor by reducing the number of components required for the generation of the two ...
    • Decoupling of multifrequency dipole antenna arrays for microwave imaging applications 

      Sáenz Sáinz, Elena Upna; Guven, K.; Ozbay, Ekmel; Ederra Urzainqui, Íñigo Upna Orcid; Gonzalo García, Ramón Upna Orcid (Hindawi Publishing Corporation, 2010)   Artículo / Artikulua  OpenAccess
      The mutual coupling between elements of a multifrequency dipole antenna array is experimentally investigated by S-parameter measurements and planar near-field scanning of the radiated field. A multifrequency array with ...

      El Repositorio ha recibido la ayuda de la Fundación Española para la Ciencia y la Tecnología para la realización de actividades en el ámbito del fomento de la investigación científica de excelencia, en la Línea 2. Repositorios institucionales (convocatoria 2020-2021).
      Logo MinisterioLogo Fecyt