Now showing items 1-20 of 112

    • 3-D printed UWB microwave bodyscope for biomedical measurements 

      Rashid, Saba; Jofre Roca, Lluís; Garrido, Alejandra; González, Giselle; Ding, Yongsheng; Aguasca Solé, Alberto; O'Callaghan Castellà, Juan Manuel; Romeu Robert, Jordi (2019-02-15)
      Article
      Open Access
      In this letter, a three-dimensional (3-D) printed compact ultrawideband (UWB) extended gap ridge horn (EGRH) antenna designed to be used for biological measurements of the human body is described. The operational frequency ...
    • A general approach for the calculation of intermodulation distortion in cavities with superconducting endplates 

      Mateu Mateu, Jordi; Collado Gómez, Juan Carlos; Menéndez Nadal, Óscar; O'Callaghan Castellà, Juan Manuel (AMER INST PHYSICS, 2003-01-31)
      Article
      Open Access
      We report on a general procedure to calculate intermodulation distortion in cavities with superconducting endplates that is applicable to the dielectric-loaded cavities currently used for measurement of surface resistance ...
    • A General approach for the calculation of intermodulation distortion in cavities with superconducting endplates 

      Mateu Mateu, Jordi; Collado Gómez, Juan Carlos; Menéndez, O; O'Callaghan Castellà, Juan Manuel (2003-01)
      Article
      Open Access
      We report on a general procedure to calculate intermodulation distortion in cavities with superconducting endplates that is applicable to the dielectric-loaded cavities currently used for measurement of surface resistance ...
    • A General Electromagnetic Simulation Tool to Predict the Microwave Nonlinear Response of Planar, Arbitrarily-Shaped HTS Structures 

      Parrón Granados, Josep; Collado Gómez, Juan Carlos; Mateu Mateu, Jordi; Rius Casals, Juan Manuel; Duffo Ubeda, Núria; O'Callaghan Castellà, Juan Manuel (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2001-03-31)
      Article
      Open Access
      This work describes a simulation tool being developed at UPC to predict the microwave nonlinear behavior of planar superconducting structures with very few restrictions on the geometry of the planar layout. The software ...
    • A general electromagnetic simulation tool to predict the microwave nonlinear response of planar, arbitrarily-shaped HTS structures 

      Parrón Granados, Josep; Collado Gómez, Juan Carlos; Mateu Mateu, Jordi; Rius Casals, Juan Manuel; Duffo Ubeda, Núria; O'Callaghan Castellà, Juan Manuel (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2001-03-31)
      Article
      Open Access
      This work describes a simulation tool being developed at UPC to predict the microwave nonlinear behavior of planar superconducting structures with very few restrictions on the geometry of the planar layout. The software ...
    • A large signal nonlinear MODFET model from small signal S-parameters 

      O'Callaghan Castellà, Juan Manuel; Beyer, James B. (Institute of Electrical and Electronics Engineers (IEEE), 1989)
      Conference report
      Open Access
      A general technique for predicting the MODFET large signal performance has been developed. The technique is based entirely on experimental data (small signal S-parameters at different biased points) and therefore is ...
    • A large signal nonlinear MODFET model from small signal S-parameters 

      O'Callaghan Castellà, Juan Manuel; Beyer, Jb (1989)
      Conference report
      Open Access
      A general technique for predicting the MODFET large signal performance has been developed. The technique is based entirely on experimental data (small signal S-parameters at different biased points) and therefore is ...
    • 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)
      Conference report
      Restricted access - publisher's policy
      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.
    • A vector approach for noise parameter fitting and selection of source admittances 

      O'Callaghan Castellà, Juan Manuel; Mondal, J. P. (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1991-08-31)
      Article
      Open Access
      Simple vector concepts can be used in the determination of noise parameters from measured data. The use of such concepts leads to a simplification in the least-square fitting algorithm, complete determination of the ...
    • A Vector Approach for Noise Parameter Fitting and Selection of Source Admittances 

      O'Callaghan Castellà, Juan Manuel (IEEE Microwave Theory and Techniques Society, 1991-08)
      Article
      Open Access
      Simple vector concepts can be used in the determination of noise parameters from measured data. The use of such concepts leads to a simplification in the least-square fitting algorithm, complete determination of the ...
    • Absorptive limiter for frequency-selective circuits 

      Collado Gómez, Juan Carlos; Hueltes Escobar, Alberto; Rocas Cantenys, Eduard; Mateu Mateu, Jordi; Booth, James C.; O'Callaghan Castellà, Juan Manuel; Verdú Tirado, Jorge Andrés (2014-06-01)
      Article
      Restricted access - publisher's policy
      This letter describes a novel absorptive limiter for frequency-selective circuits. The proposed circuit allows the design of absorptive limiters based on a bi-state phase shifter, which is appropriate for integration into ...
    • Accuracy considerations in microstrip surface impedance measurements 

      O'Callaghan Castellà, Juan Manuel; Sans, C.; Collado Gómez, Juan Carlos; Canet Grau, Eduard; Pous Andrés, Rafael; Fontcuberta, Josep (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1997-06-30)
      Article
      Open Access
      An approach is proposed for the design, measurement and data extraction of superconducting microstrip resonators used in determination of surface resistance and penetration depth. Major sources of error are analyzed and ...
    • Accuracy considerations in surface impedance measurements 

      O'Callaghan Castellà, Juan Manuel; Sans, C; Pous Andrés, Rafael; Collado Gómez, Juan Carlos; Canet, E (1997-06)
      Article
      Open Access
      An approach is proposied for the design, measurement and data extraction of superconducting microstrip resonators used in determination of surface resistance and penetration depth. Major sources of error are analyzed and ...
    • Analysis and Simulation of Distributed Nonlinearities in Ferroelectrics and superconductors for Microwave Applications 

      Seron, David; Collado Gómez, Juan Carlos; Mateu Mateu, Jordi; O'Callaghan Castellà, Juan Manuel (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006-03-31)
      Article
      Open Access
      This paper gives closed-form equations for the intermodulation and third harmonic signals generated in a nonlinear transmission line with distributed quadratic nonlinearities in the conductor and dielectric. Although the ...
    • Analysis and Simulation of the Effects of Distributed Nonlinearities in Microwave Superconducting Devices 

      Collado Gómez, Juan Carlos; Mateu Mateu, Jordi; O'Callaghan Castellà, Juan Manuel (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2005-03-31)
      Article
      Open Access
      This paper presents a comprehensive study of microwave nonlinearities in superconductors, with an emphasis on intermodulation distortion and third-harmonic generation. It contains the analysis of various resonant and ...
    • Analysis of dielectric-loaded cavities for characterization of the nonlinear properties of high temperature superconductors 

      Mateu Mateu, Jordi; Collado Gómez, Juan Carlos; Menéndez Nadal, Óscar; O'Callaghan Castellà, Juan Manuel (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2003-06-30)
      Article
      Open Access
      This work describes and compares two alternative methods of analyzing dielectric-loaded cavities for measurement of intermodulation distortion in HTS films. One of them is based on assuming a specific type of HTS nonlinearities ...
    • Application of selective leaching in fabrication of thin film ybco devices 

      James, P. M.; O'Callaghan Castellà, Juan Manuel (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1993-03-31)
      Article
      Open Access
      Ethylenediamine solutions have been shown to turn bulk YBCO into insulating materials. The effect of these solutions on thin YBCO films is studied. In both unpatterned and patterned films, a smooth decrease in critical ...
    • Application of selective leaching in fabrication of thin film ybco devices 

      James, Pm; O'Callaghan Castellà, Juan Manuel (1993-03)
      Article
      Open Access
      Ethylenediamine solutions have been shown to turn bulk YBCO into insulating materials. The effect of these solutions on thin YBCO films is studied. In both unpatterned and patterned films, a smooth decrease in critical ...
    • Banco automatizado para la medida de parámetros S, de ruido y características DC de transistores en oblea 

      Pradell i Cara, Lluís; Purroy, Francesc; Subirats, M.; Ballester, A.; Torres Torres, Francisco; O'Callaghan Castellà, Juan Manuel; Corbella Sanahuja, Ignasi (1994)
      Conference report
      Open Access
      The AMR Group has an automatized bench for the measurement of DC-characteristics, [S] parameters (45 MHz- 40 GHz) and noise parameters (2-26.5 GHz) of microwave on-wafer transistors. The hardware configuration is described, ...
    • Coated conductor technology for the beamscreen chamber of future high energy circular colliders 

      Puig Molina, Teresa; Krkotic, Patrick; Romanov, Artur; O'Callaghan Castellà, Juan Manuel; Gutiérrez Royo, Joffre (2019-09-01)
      Article
      Open Access
      The surface resistance of state-of-the-art REBa2Cu3O7-x coated conductors has been measured at 8 GHz versus temperature and magnetic field. We show that the surface resistance of REBa2Cu3O7-x strongly depends on the ...