Ara es mostren els items 13-32 de 254

    • A figure of merit to assess the performance of photoconductive antennas at terahertz band 

      Romeu Robert, Jordi; Cea Falcó, Marc de; Jofre Roca, Lluís; Yazgan, Ahmet Utku (Institute of Electrical and Electronics Engineers (IEEE), 2017)
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      Photoconductive antennas are one of the most efficient ways to radiate and receive EM waves around the 1 THz frequency band. The physical processes involved in photoconductive terahertz signal generation are complex enough ...
    • A figure-of-merit for pattern reconfigurable antennas 

      Rodrigo López, Daniel; Romeu Robert, Jordi; Capdevila Cascante, Santiago; Jofre Roca, Lluís (2013-03)
      Article
      Accés restringit per política de l'editorial
      The performance of pattern reconfigurable antennas is evaluated with the purpose of deriving a figure-of-merit for pattern reconfigurability. A general formulation is provided for the average gain achieved by a ...
    • A frequency reconfigurable cell for beam-scanning reflectarrays 

      Rodrigo López, Daniel; Jofre Roca, Lluís; Perruisseau Carrier, Julien (Institute of Electrical and Electronics Engineers (IEEE), 2013)
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      Reflectarray antennas are excellent candidates for beam-scanning applications thanks to their low loss, light and quasi-planar structure and ease of electronic control. However, reflectarray antennas suffer from narrower ...
    • A near field spherical wave inverse synthetic aperture radar technique 

      Broquetas Ibars, Antoni; Jofre Roca, Lluís; Cardama Aznar, Ángel (Institute of Electrical and Electronics Engineers (IEEE), 1992)
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      The authors present an imaging near-field spherical wave inverse synthetic aperture radar (SWISAR) algorithm based on a focusing operator of the scattered fields on the target surface. A spherical wave can be easily generated ...
    • A new class of antenna array with a reconfigurable element factor 

      Li, Zhouyuan; Rodrigo López, Daniel; Jofre Roca, Lluís; Cetiner, Bedri Artug (2013-04)
      Article
      Accés restringit per política de l'editorial
      A parasitic layer-based multifunctional reconfigurable antenna array (MRAA) formed by the linear combination of four (4 1) identical multifunctional reconfigurable antenna (MRA) elements is presented. Each MRA produces ...
    • A novel compact UHF wideband antenna for near field electrical characterization of Steel Fiber Reinforced Concrete 

      Roqueta Crusats, Gemma; Irteza, I; Romeu Robert, Jordi; Jofre Roca, Lluís (IEEE Computer Society Publications, 2009)
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      A novel, electrically small, UHF (350 MHz–750 MHz)microstrip slot antenna is presented. The antenna is designed for the characterization of Steel Fiber Reinforced Concrete (SFRC) segments. The antenna consists on a three ...
    • A quad-band antenna for public safety applications 

      Mopidevi, Hema Swaroop; Damgaci, T; Rodrigo López, Daniel; Jofre Roca, Lluís; Cetiner, Bedri Artug (2014-01-01)
      Article
      Accés restringit per política de l'editorial
      The design, fabrication, and characterization of a frequency-reconfigurable antenna for the United States Public Safety (PS) wireless communication applications are presented. This antenna is quad-band operating in the PS ...
    • A reconfigurable antenna with beam steering and beamwidth variability for wireless communications 

      Towfiq, Asaduzzaman; Bahceci, Israfil; Blanch Boris, Sebastián; Romeu Robert, Jordi; Jofre Roca, Lluís; Cetiner, Bedri Artug (2018-07-12)
      Article
      Accés obert
      A reconfigurable antenna (RA) capable of steering its beam into the hemisphere corresponding to ¿ ¿ {-40°,0°,40°}, Ø ¿ {0°,45°,90°,-45°}, and of changing 3-dB beamwidth, where ¿3dB ¿ (40°,100°), Ø ¿ {45°,90°,-45°} for ...
    • A submillimeter wave parabolic reflector by additive manufacturing 

      Romeu Robert, Jordi; Aguasca Solé, Alberto; Blanch Boris, Sebastián; O'Callaghan Castellà, Juan Manuel; Jofre Roca, Lluís; Buitrago Ventura, Santiago (Institute of Electrical and Electronics Engineers (IEEE), 2018)
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      The manufacturing of prototype of an offset parabolic reflector to operate at 120 GHz is presented. The paper describes the different metallization options to achieve a good performance.
    • Active microwave computed brain tomography: The response to a challenge 

      Broquetas Ibars, Antoni; Jofre Roca, Lluís (1991-02)
      Article
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      The potential application of active microwave techniques to brain imaging is studied by numerical simulations and experimentally using a recently developed cylindrical microwave scanner. The potential advantages and ...
    • Active microwave imaging of inhomogeneous bodies 

      PICHOT DU MEZERAY, Christian; Jofre Roca, Lluís; Peronnet, Guy; Bolomey, Jean Charles (1986-04-01)
      Article
      Accés obert
      A numerical method and experimental technique for microwave imaging of inhomogenous bodies is presented. This method is based on the interpretation of the diffraction phenomena and leads to tomographic reconstruction of ...
    • Active microwave imaging: a cylindrical system for biomedical applications 

      Jofre Roca, Lluís; Broquetas Ibars, Antoni; Hawley, Mark (1988)
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      The authors examine the use of active microwave tomography as an imaging technique which gives information on the dielectric properties of the body. They show that a cylindrical system is an efficient option to obtain ...
    • Active microwave sensing of highly contrasted dielectric bodies 

      Broquetas Ibars, Antoni; Mallorquí Franquet, Jordi Joan; Rius Casals, Juan Manuel; Jofre Roca, Lluís; Cardama Aznar, Ángel (1993-11)
      Article
      Accés restringit per política de l'editorial
      In this work the active tomographic imaging of biological bodies which exhibits a high dielectric contrast is studied. Two approaches based on the Born approximation are presented: a differential reconstruction method which ...
    • Adaptive beamwidth optimization under Doppler ICI and positioning errors at mmWave bands 

      Ballesteros Sánchez, Christian; Pfadler, Andreas; Montero Bayo, Luca; Romeu, Jordi; Jofre Roca, Lluís (Elsevier, 2022-04-01)
      Article
      Accés obert
      The growing trends towards massive antenna arrays with focusing capabilities has enabled the use of higher frequencies at the cost of more complex systems. In the particular case of vehicular communications, millimeter-wave ...
    • Admitancia de entrada de una guía rectangular rellena de dieléctrico 

      Jofre Roca, Lluís; Ferrando Bataller, Miquel; Cardama Aznar, Ángel (Unión Científica Internacional de Radio (URSI), 1983)
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      A variational formulation, based in a plane wave angular decomposition, is developped for the admitance of a rectangular dielectric-filled waveguide, radiating in a half space.
    • Agrupación plana alimentada por linea de sustrato suspendido 

      Torrents Dolz, Josep M.; Romeu Robert, Jordi; Jofre Roca, Lluís (1989)
      Text en actes de congrés
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      The purpose of this design is a new type of planar antenna with hi gh-efficency and large-bandwidth requirements of TVRO. A low loss suspended substrate line (SSL ) has been developed and optimisated for feed network.
    • Algoritmo iterativo de propagación espectral para el cálculo de RCS en cavidades conductoras 

      Rius Casals, Juan Manuel; Cardama Aznar, Ángel; Jofre Roca, Lluís (1992)
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      One of the most difficult problems in the RCS prediction of a complex target is the analysis of the cavities existing at the air inlets and outlets of engines. The geometrical complexity of these structures makes difficult ...
    • Algoritmos de tomografía de microondas para objetos de alto contraste 

      Broquetas Ibars, Antoni; Jofre Roca, Lluís (Universidad Politécnica de Madrid (UPM), 1988)
      Text en actes de congrés
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      Conventional first order algorithms used in microwave tomography often fail to reconstruct biological bodies due to their high contrast in permittivity. The paper presents several methods to improve the applicability of ...
    • Algoritmos de tomografía de microondas para objetos de alto contrastre 

      Broquetas Ibars, Antoni; Ferrando Bataller, Miquel; Jofre Roca, Lluís (Universidad Politécnica de Madrid (UPM), 1988)
      Text en actes de congrés
      Accés obert
      Conventional first order algorithms used in microwave tomography often fail to reconstruct biological bodies due to their high contrast in permittivity. The paper presents several methods to improve the applicability of ...
    • Algoritmos para el cálculo de los campos lejanos radiados por antenas, a partir de medidas en campo próximo 

      Jofre Roca, Lluís; Cardama Aznar, Ángel (1980)
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      We present the principles of operation of near field antenna ranges and general expressions for the calculation of the far field, from measurements on plane surfaces, focusing on the limitations of the different aproaches. ...