Now showing items 17-36 of 292

    • BOTDA measurements tolerant to non-local effects by using a phase-modulated probe wave and RF demodulation 

      Urricelqui Polvorinos, Javier Upna; Sagüés García, Mikel Upna; Loayssa Lara, Alayn Upna (Optical Society of America, 2013)   Artículo / Artikulua  OpenAccess
      We demonstrate a Brillouin optical time domain analysis sensor based on a phase modulated probe wave and RF demodulation that provides measurements tolerant to frequency dependent variations of the pump pulse power induced ...
    • Brillouin optical time-domain analysis sensor assisted by Brillouin distributed amplification of pump pulses 

      Urricelqui Polvorinos, Javier Upna; Sagüés García, Mikel Upna; Loayssa Lara, Alayn Upna (Optical Society of America, 2015)   Artículo / Artikulua  OpenAccess
      We demonstrate the extension of the measurement range of Brillouin optical time-domain analysis (BOTDA) sensors using a distributed Brillouin amplifier (DBA). The technique is based on injecting a DBA pump wave in the ...
    • Brillouin optical time-domain analysis sensor with pump pulse amplification 

      Mompó Roselló, Juan José Upna; Urricelqui Polvorinos, Javier Upna; Loayssa Lara, Alayn Upna (Optical Society of America, 2016)   Artículo / Artikulua  OpenAccess
      We demonstrate a simple technique to provide conventional Brillouin optical time-domain analysis sensors with mitigation for pump pulse attenuation. The technique is based on operating the sensor in loss configuration so ...
    • Broadband frequency and angular response of a sinusoidal bull’s eye antenna 

      Beaskoetxea Gartzia, Unai Upna; Navarro Cía, Miguel Upna; Beruete Díaz, Miguel Upna (IOP Publishing, 2016)   Artículo / Artikulua  OpenAccess
      A thorough experimental study of the frequency and beaming angle response of a metallic leaky-wave bull’s eye antenna working at 77 GHz with a sinusoidally corrugated profile is presented. The beam scanning property of ...
    • Broadband radar cross-section reduction using AMC technology 

      Iriarte Galarregui, Juan Carlos Upna; Tellechea Pereda, Amagoia Upna; Martínez de Falcón, José Luis Upna; Ederra Urzainqui, Íñigo Upna; Gonzalo García, Ramón Upna; Maagt, Peter de (IEEE, 2013)   Artículo / Artikulua  OpenAccess
      This paper presents the design, fabrication and characterization of a planar broadband chessboard structure to reduce the radar cross-section (RCS) of an object. The chessboard like configuration is formed by combining two ...
    • Broadband spoof plasmons and subwavelength electromagnetic energy confinement on ultrathin metafilms 

      Navarro Cía, Miguel Upna; Beruete Díaz, Miguel Upna; Agrafiotis, Spyros; Falcone Lanas, Francisco Javier Upna; Sorolla Ayza, Mario Upna; Maier, Stefan A. (Optical Society of America, 2009)   Artículo / Artikulua  OpenAccess
      A complementary split ring resonator (CSRR)-based metallic layer is proposed as a route to mimic surface plasmon polaritons. A numerical analysis of the textured surface is carried out and compared to previous prominent ...
    • Challenges in wireless system integration as enablers for indoor context aware environments 

      López Iturri, Peio Upna; Aguirre Gallego, Erik Upna; Azpilicueta Fernández de las Heras, Leyre Upna; Astrain Escola, José Javier Upna; Villadangos Alonso, Jesús Upna; Falcone Lanas, Francisco Javier Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      The advent of fully interactive environments within Smart Cities and Smart Regions requires the use of multiple wireless systems. In the case of user-device interaction, which finds multiple applications such as Ambient ...
    • Characterization of microring filters for differential group delay applications 

      Doménech, D.; Chamorro Posada, P.; Fraile Pelaez, F.J.; Erro Betrán, María José Upna; Tainta Ausejo, Santiago Upna; Muriel, M.A.; Baños, R.; Bolten, J.; Kleinjans, H. (IEEEOptical Society of America, 2017)   Artículo / Artikulua  OpenAccess
      The longitudinal offset technique permits to improve the accuracy of the coupling coefficients of integrated directional couplers and provides designs that can be easily implemented with current fabrication tolerances. ...
    • Characterization of wireless channel impact on wireless sensor network performance in public transportation buses 

      Azpilicueta Fernández de las Heras, Leyre Upna; López Iturri, Peio Upna; Aguirre Gallego, Erik Upna; Astrain Escola, José Javier Upna; Villadangos Alonso, Jesús Upna; Zubiri Segura, Cristóbal; Falcone Lanas, Francisco Javier Upna (IEEE, 2015)   Artículo / Artikulua  OpenAccess
      Wireless communications systems are growing rapidly during the last two decades and they are gaining a significant role for multiple communication tasks within public transportation buses. In this work, the impact of ...
    • Chirping techniques to maximize the power-handling capability of harmonic waveguide low-pass filters 

      Teberio Berdún, Fernando Upna; Arregui Padilla, Iván Upna; Gómez Torrent, Adrián Upna; Arnedo Gil, Israel Upna; Chudzik, Magdalena Upna; Zedler, Michael; Goertz, Franz-Josef; Jost, Rolf; Lopetegui Beregaña, José María Upna; Gómez Laso, Miguel Ángel Upna (IEEE, 2016)   Artículo / Artikulua  OpenAccess
      A novel chirping technique is applied to the design of very high-power waveguide harmonic low-pass filters. The technique could be used, for instance, to avoid multipactor testing in multicarrier systems such as the ...
    • Circuit and multipolar approaches to investigate the balance of powers in 2D scattering problems 

      Liberal Olleta, Íñigo Upna; Ederra Urzainqui, Íñigo Upna; Gonzalo García, Ramón Upna; Ziolkowski, Richard W. (EMW Publishing, 2013)   Artículo / Artikulua  OpenAccess
      Circuit and multipolar approaches are presented to investigate the correlation between absorption and scattering processes in 2D problems. This investigation was inspired by earlier works of Prof.R.E. Collin, which pointed ...
    • Circuit approach to the minimal configuration of terahertz anomalous extraordinary transmission 

      Beruete Díaz, Miguel Upna; Navarro Cía, Miguel Upna; Kuznetsov, Sergei A.; Sorolla Ayza, Mario Upna (American Institute of Physics, 2011)   Artículo / Artikulua  OpenAccess
      In this letter we present an in-depth circuit analysis of anomalous extraordinary transmission ET through subwavelength slit and hole arrrays loaded by a dielectric slab. We show the key role played by the thickness of the ...
    • Compact and highly-efficient polarization independent vertical resonant couplers for active-passive monolithic integration 

      Galarza Galarza, Marko; Thourhout, Dries Van; Baets, Roel; López-Amo Sáinz, Manuel Upna (Optical Society of America, 2008)   Artículo / Artikulua  OpenAccess
      Compact low-loss polarization independent vertical coupling between a 1.55 μm InGaAsP bulk active waveguide and a passive waveguide based on bimodal interference is presented. Simulation results show low coupling loss (<0.1 ...
    • Compact ultra wide band microstrip bandpass filter based on multiple-mode resonator and modified complementary split ring resonator 

      Marcotegui Iturmendi, José Antonio Upna; Illescas, Jesús; Estévez, Aritz; Falcone Lanas, Francisco Javier Upna (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 ...
    • Comparative study of layer-by-layer deposition techniques for poly(sodium phosphate) and poly (allylamine hydrochloride) 

      Elosúa Aguado, César Upna; López Torres, Diego Upna; Hernáez Sáenz de Zaitigui, Miguel Upna; Matías Maestro, Ignacio Upna; Arregui San Martín, Francisco Javier Upna (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 ...
    • A comparative study of two different approaches for the incorporation of silver nanoparticles into layer-by-layer films 

      Rivero Fuente, Pedro José Upna; Goicoechea Fernández, Javier Upna; Matías Maestro, Ignacio Upna; Arregui San Martín, Francisco Javier Upna (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; Campo Bescós, Miguel Ángel Upna; López Rodríguez, José Javier; Yerro Lizarazu, David; Elosúa Aguado, César Upna; Arregui San Martín, Francisco Javier Upna; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel Upna (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; López-Amo Sáinz, Manuel Upna (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. ...
    • A comprehensive analysis of the absorption spectrum of conducting ferromagnetic wires 

      Liberal Olleta, Íñigo Upna; Ederra Urzainqui, Íñigo Upna; Gómez Polo, Cristina; Labrador Otamendi, Alberto; Pérez de Landazábal Berganzo, José Ignacio; Gonzalo García, Ramón Upna (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; Urtasun Erburu, Andoni Upna; Ursúa Rubio, Alfredo Upna; Sanchis Gúrpide, Pablo Upna (Elsevier, 2018)   Artículo / Artikulua
      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 ...