Exploració per tema "Microwave measurements"

Ara es mostren els items 1-20 de 40

    • A high-resolution UWB IR superregenerative receiver front end with an SRD quench shaper 

      Moncunill Geniz, Francesc Xavier; Bonet Dalmau, Jordi; Palà Schönwälder, Pere; Águila López, Francisco del; Giralt Mas, Ma. Rosa (2012-02-03)
      Article
      Accés restringit per política de l'editorial
      We present a simple receiver front end that makes use of the baseband superregeneration principle to detect ultrawideband (UWB) impulse radio signals. The UWB antenna is directly connected to the core circuit consisting ...

    • A two-dimensional doppler-radiometer for earth observation 

      Camps Carmona, Adriano José; Swift, Calvin T. (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2001-07-31)
      Article
      Accés obert
      Compared to synthetic aperture radars (SARs), the angular resolution of microwave radiometers is quite poor. Traditionally, it has been limited by the physical size of the antenna. However, the angular resolution can be ...

    • 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
      Accés obert
      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 ...

    • 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
      Accés obert
      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 ...

    • Accurate determination of dielectric properties in small, high-permittivity dielectric cylinders 

      Tagdulang, Nikki; Krkotic, Patrick; Díez, A.; Pont Montaner, Montserrat; O'Callaghan Castellà, Juan Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2022)
      Comunicació de congrés
      Accés obert
      We describe a method for performing cryogenic permittivity and loss tangent measurements of small (few mm), high-permittivity dielectric cylinders used in surface impedance measurement of superconductors. We combine the ...

    • Analysis of Correlation and Total Power Radiometer Front-Ends Using Noise Waves 

      Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Camps Carmona, Adriano José; Duffo Ubeda, Núria; Vall-Llossera Ferran, Mercedes Magdalena; Rautiainen, Kimmo; Martín Neira, Manuel; Colliander, Andreas (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2005-11-30)
      Article
      Accés obert
      A complete and systematic noise analysis of radiometer front-ends, including both total power and correlation measurements, is presented. The procedure uses the concepts of noise waves and S-parameters, widely used in ...

    • Analysis of correlation and total power radiometer front-ends using noise waves 

      Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Camps Carmona, Adriano José; Duffo Ubeda, Núria; Vall-Llossera Ferran, Mercedes Magdalena; Rautiainen, Kimmo; Martín Neira, Manuel; Colliander, Andreas (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2005-11-30)
      Article
      Accés obert
      A complete and systematic noise analysis of radiometer front-ends, including both total power and correlation measurements, is presented. The procedure uses the concepts of noise waves and S-parameters, widely used in ...

    • Automatic calibration of channels frequency response in interferometric radiometers 

      Camps Carmona, Adriano José; Torres Torres, Francisco; Bará Temes, Francisco Javier; Corbella Sanahuja, Ignasi; Monzón Soria, Francisco Jose (IEE-INST ELEC ENG, 1999-01-31)
      Article
      Accés obert
      The large field of view required in Earth observation interferometric radiometers does not enable the use of a variable delay to compensate for different transit times, as in radioastronomy. A technique is presented to ...

    • Bidimensional scattering of tm and te polarized waves by dielectric 

      Mallorquí Franquet, Jordi Joan; Vaquer Bonnin, Miguel; Cardama Aznar, Ángel; Jofre Roca, Lluís (EUROPEAN MICROWAVE CONFERENCE MANAGEMENT COMMITEE REED EXHIBITION COMPANIES, 1993)
      Text en actes de congrés
      Accés obert
      In the study of electromagnetic radiation effects over dielectric bodies, effective numerical methods are needed. At present, there is a lack of tools for measuring this effects and due to the huge growth of microwave ...

    • Comparison between nonlinear measurements in patterned and unpatterned thin films 

      Collado Gómez, Juan Carlos; Mateu Mateu, Jordi; O'Callaghan Castellà, Juan Manuel (IOP PUBLISHING LTD, 2004-07-31)
      Article
      Accés obert
      This work compares two alternative methods of characterizing the nonlinearities in a 10 × 10 mm2 superconducting thin film. Both methods are based on measuring the intermodulation distortion in high temperature superconducting ...

    • Considerations about antenna pattern measurements of 2-D aperture synthesis radiometers 

      Camps Carmona, Adriano José; Skou, Neils; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria (IEEE, 2006-04-30)
      Article
      Accés obert
      Accurate measurement of the antenna voltage patterns of large-aperture synthesis radiometers is critical in order to achieve good radiometric accuracy, and a very time consuming and expensive task. Measurement requirements ...

    • Convergence and stability assessment of Newton-Kantorovich reconstrutin algorithms for microwve tomography 

      Joachimowicz, N.; Mallorquí Franquet, Jordi Joan; Bolomey, J. C. (Jean-Charles); Broquetas Ibars, Antoni (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1998-08-31)
      Article
      Accés obert
      For newly developed iterative Newton-Kantorovitch reconstruction techniques, the quality of the final image depends on both experimental and model noise. Experimental noise is inherent to any experimental acquisition scheme, ...

    • Database of "in vivo" measurements for quantitative microwave imaging and reconstruction algorithms available 

      Mallorquí Franquet, Jordi Joan; Joachimowicz, N; Bolomey, Jean Charles; Broquetas Ibars, Antoni (1995-10)
      Article
      Accés obert

    • Deforming and relief interferometric SAR imaging at W-band 

      Abril, Jordi; Nova, Enrique; Broquetas Ibars, Antoni; Aguasca Solé, Alberto; Romeu Robert, Jordi; Jofre Roca, Lluís (IEEE, 2011)
      Text en actes de congrés
      Accés restringit per política de l'editorial
      Interferometry at W Band can be exploited to form images of small deformations with precisions in the order of tenths of microns and retrieve surface relieves. An Interferometric Synthetic Aperture Radar setup is proposed ...

    • Denormalization of visibilities for in-orbit calibration of interferometric radiometers 

      Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Camps Carmona, Adriano José; Duffo Ubeda, Núria; Vall-Llossera Ferran, Mercedes Magdalena; Beraza Robledano, Santiago; Gutiérrez, C.; Martín Neira, Manuel (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006-10-31)
      Article
      Accés obert
      This paper reviews the relative calibration of an interferometric radiometer taking into account the experimental results of the first batch of receivers developed in the frame of the European Space Agency's Soil Moisture ...

    • Downscaling SMOS-derived soil moisture using MODIS visible/infrared data 

      Piles, Maria; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena; Corbella Sanahuja, Ignasi; Panciera, Rocco; Ruediger, Christoph; Kerr, Yann H.; Walker, Jeffrey (IEEE Press. Institute of Electrical and Electronics Engineers, 2011-09)
      Article
      Accés restringit per política de l'editorial
      A downscaling approach to improve the spatial resolution of Soil Moisture and Ocean Salinity (SMOS) soil moisture estimates with the use of higher resolution visible/infrared (VIS/IR) satellite data is presented. The ...

    • Extension of Kirchhoff method under stationary phase approximation to determination of polarimetric thermal emission from the sea 

      Camps Carmona, Adriano José; Corbella Sanahuja, Ignasi; Rius Casals, Juan Manuel (IEE-INST ELEC ENG, 1998-07-31)
      Article
      Accés obert
      Wind direction over the sea can be determined from radiometric measurements of the third Stokes parameter (TU). The Kirchhoff method is extended under the stationary phase approximation to compute the dependence of TU on ...

    • Fet noise-parameter determination using a novel technique based on 50 noise measurements 

      Lázaro Guillén, Antoni; Pradell i Cara, Lluís; O'Callaghan Castellà, Juan Manuel (IEEE, 1999)
      Article
      Accés obert
      A novel method for measuring the four noise parameters of a field-effect transistor (FET) is presented. It is based on the determination of its intrinsic noise matrix elements [C11INT, C22INT, Re(C12 INT), Im(C12INT)] by ...

    • Inter-islands optical link tests 

      Comerón Tejero, Adolfo; Bará Temes, Francisco Javier (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1990-05-01)
      Article
      Accés obert
      Free-space optical communication systems between satellites and also between a satellite and a ground station foreseen in Europe in the mid-1990's require far-field on-ground experimentation prior to launch. To identify ...

    • L-band vegetation optical depth estimation using transmitted GNSS signals: Application to GNSS-reflectometry and positioning 

      Camps Carmona, Adriano José; Alonso Arroyo, Alberto; Hyuk, Park; Onrubia Ibáñez, Raúl; Pascual Biosca, Daniel; Querol Borràs, Jorge (Multidisciplinary Digital Publishing Institute (MDPI), 2020-08-01)
      Article
      Accés obert
      At L-band (1–2 GHz), and particularly in microwave radiometry (1.413 GHz), vegetation has been traditionally modeled with the τ-ω model. This model has also been used to compensate for vegetation effects in Global Navigation ...