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  • Fast computation of an infinite, longitudinally-varying and harmonic strip load acting on a viscoelastic half-space

     Arcos Villamarin, Robert; Clot Razquin, Arnau; Romeu Robert, Jordi; Martin Román, Sara-regina
    European journal of mechanics. A, Solids
    Date of publication: 2014-02-01
    Journal article

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  • A figure-of-merit for pattern reconfigurable antennas

     Rodrigo Lopez, Daniel; Romeu Robert, Jordi; Capdevila Cascante, Santiago; Jofre Roca, Luis
    IEEE transactions on antennas and propagation
    Date of publication: 2013-03
    Journal article

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  • Multiport small integrated antenna impedance matrix measurement by backscattering modulation

     Monsalve, Beatriz; Blanch Boris, Sebastian; Romeu Robert, Jordi
    IEEE transactions on antennas and propagation
    Date of publication: 2013-01
    Journal article

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    A method to characterize small antennas in their actual operating conditions is presented. The proposed procedure is based on the radar cross section (RCS) measurement technique using backscattering modulation. A theoretical description of the measurement setup based on the signal flow graph representation is presented. The experimental validation includes the measurement of one and two port antennas, as well as the measurement of a small integrated antenna. Results show how the effect of the environment on the antenna impedance can be adequately measured with the proposed system.

    A method to characterize small antennas in their actual operating conditions is presented. The proposed procedure is based on the radar cross section (RCS) measurement technique using backscattering modulation. A theoretical description of the measurement setup based on the signal flow graph representation is presented. The experimental validation includes the measurement of one and two port antennas, as well as the measurement of a small integrated antenna. Results show how the effect of the environment on the antenna impedance can be adequately measured with the proposed system.

  • Antenna input impedance measurement using multi-load MST

     Romeu Robert, Jordi; Capdevila Cascante, Santiago; Bolomey, Jean Charles; Jofre Roca, Luis
    International Workshop on Antenna Technology
    Presentation's date: 2013-03
    Presentation of work at congresses

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    This paper presents the practical use of modulated scatterer technique (MST) for the measurement of the antenna input impedance using a multi-load automatic switching device, and it also includes the analysis of the measurement error as a function of the selected loads in the MST circuitry

  • Characterization of pharmaceuticals using Terahertz Time Domain spectral-tomography

     Nova Lavado, Enrique; Roqueta Crusats, Gemma; Romeu Robert, Jordi; Jofre Roca, Luis
    European Conference on Antennas and Propagation
    Presentation's date: 2013
    Presentation of work at congresses

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    In this paper a Terahertz Time-Domain measurement system has been used to perform Tomographic imaging of pharmaceutical compounds with coating. Measurements on paracetamol and ibuprofene samples are done both in transmission and reflection geometries and their capabilities are compared. Results of the contrast reconstructions provide information of the relative permittivity of the pharmaceutical compounds. The interfaces between materials with different permittivities are detected, thus allowing characterization of different layers of the compound.

    In this paper a Terahertz T ime-Domain measurement system has been used to perform Tomographic imaging of pharmaceutical compounds with coating. Measurements on paracetamol and ibuprofene samples are done both in transmission and reflection geometries and their capabilities are compared. Results of the contrast reconstructions provide information of the relative permittivity of the pharmaceutical compounds. T he interfaces between materials with different permittivities are detected, thus allowing characterization of different layers of the compound.

  • Design of a dielectric flat lens antenna for 60 GHz WPAN applications

     Imbert Villa, Marc; Romeu Robert, Jordi; Jofre Roca, Luis
    IEEE International Symposium on Antennas and Propagation
    Presentation's date: 2013-07
    Presentation of work at congresses

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    In this paper we present the design of a dielectric flat lens antenna to operate in the 60 GHz band for WPAN applications. In order to overcome the specific atmospheric attenuation, which characterizes the propagation in the 60 GHz band, high directive antennas are required. Moreover, due to high user random mobility in indoor environments, beam-steerable antennas are also needed. For these reasons, we propose a design based on a dielectric flat lens antenna with scanning capabilities from -30° to +30° with around 20 dB of gain in the whole entire band of interest (57 to 66 GHz), and up to ±60° of beam-steering capabilities with around 15 dB of gain. The dielectric flat lens also leads to low-profile antenna configuration, easy to manufacture and low-cost, in order to integrate the design together with a commercial RF CMOS chip.

  • Radiometric and spatial resolution constraints in millimeter-mave close-range passive screener systems

     Nova Lavado, Enrique; Romeu Robert, Jordi; Torres Torres, Francisco; Pablos Hernandez, Miriam; Riera Salis, Jose Manuel; Broquetas Ibars, Antoni; Jofre Roca, Luis
    IEEE transactions on geoscience and remote sensing
    Date of publication: 2013-04
    Journal article

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    This paper presents a comparative study of the radiometric sensitivity and spatial resolution of three near-field (NF) passive screener systems: real aperture, 1-D synthetic aperture (SA), and 2-D SA radiometers are compared. The analytical expressions for the radiometric resolution, the number of required antennas, and the number of pixels in the image are derived taking into account the distortion produced by the NF geometry at nonboresight directions where the distortion is dominant. Based on the theoretical results, a performance comparison among the studied systems is carried out to show the advantages and drawbacks when using the radiometers in a close-range screening application. Moreover, the screener performance in a close-range environment is discussed from the results obtained in the aforementioned comparison.

  • Millimeter-Wave and Terahertz Imaging Techniques  Open access

     Nova Lavado, Enrique
    Defense's date: 2013-07-22
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    This thesis presents the development and assessment of imaging techniques in the millimeterwave (mmW) and terahertz frequency bands. In the first part of the thesis, the development of a 94 GHz passive screener based on a total-power radiometer (TPR) with mechanical beamscanning is presented. Several images have been acquired with the TPR screener demonstrator, either in indoor and outdoor environments, serving as a testbed to acquire the know-how required to perform the research presented in the following parts of the thesis. In the second part of the thesis, a theoretical research on the performance of near-field passive screeners is described. This part stands out the tradeoff between spatial and radiometric resolutions taking into account the image distortion produced by placing the scenario in the near-field range of the radiometer array. In addition, the impact of the decorrelation effect in the image has been also studied simulating the reconstruction technique of a synthetic aperture radiometer. Guidelines to choose the proper radiometer depending on the application, the scenario, the acquisition speed and the tolerated image distortion are given in this part. In the third part of the thesis, the development of a correlation technique with optical processing applicable to millimeter-wave interferometric radiometers is described. The technique is capable of correlating wide-bandwidth signals in the optical domain with no loss of radiometric sensitivity. The theoretical development of the method as well as measurements validating the suitability to correlate radiometric signals are presented in this part. In the final part of the thesis, the frequency band of the imaging problem is increased to frequencies beyond 100 GHz, covering the THz band. In this case the research is centered in tomographic techniques that include spectral information of the samples in the reconstructed images. The tomographic algorithm can provide detection and identification of chemical compounds that present a certain spectral footprint in the THz frequency band.

  • Waves and Systems

     Romeu Robert, Jordi
    Participation in a competitive project

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  • Radiometric and spatial resolution constraints in millimeter-wave close-range passive screener systems

     Nova Lavado, Enrique; Romeu Robert, Jordi; Torres Torres, Francisco; Pablos, M.; Riera, J.M.; Broquetas Ibars, Antoni; Jofre Roca, Luis
    IEEE transactions on geoscience and remote sensing
    Date of publication: 2013-04
    Journal article

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    This paper presents a comparative study of the radiometric sensitivity and spatial resolution of three near-field (NF) passive screener systems: real aperture, 1-D synthetic aperture (SA), and 2-D SA radiometers are compared. The analytical expressions for the radiometric resolution, the number of required antennas, and the number of pixels in the image are derived taking into account the distortion produced by the NF geometry at nonboresight directions where the distortion is dominant. Based on the theoretical results, a performance comparison among the studied systems is carried out to show the advantages and drawbacks when using the radiometers in a close-range screening application. Moreover, the screener performance in a close-range environment is discussed from the results obtained in the aforementioned comparison.

  • Enhancing RFID sensing capabilities: multi-load backscattering

     Capdevila Cascante, Santiago; Jofre Roca, Luis; Romeu Robert, Jordi; Bolomey, Jean Charles
    IEEE International Symposium on Antennas and Propagation
    Presentation's date: 2013-07
    Presentation of work at congresses

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    This conference paper presents some experimental results using the concept of an multi-loaded enhanced RFID tag capable of switching between different loads to fully determine the input impedance of the RFID tag antenna which can then be used for sensing applications.

  • 94 GHz cassegrain reflector antenna performance characterization

     Nova Lavado, Enrique; Rodrigo Lopez, Daniel; Romeu Robert, Jordi; Jofre Roca, Luis
    European Conference on Antennas and Propagation
    Presentation's date: 2012
    Presentation of work at congresses

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  • Interference rejection using frequency and pattern reconfigurable antennas

     Rodrigo Lopez, Daniel; Romeu Robert, Jordi; Jofre Roca, Luis
    IEEE International Symposium on Antennas and Propagation
    Presentation's date: 2012-07-13
    Presentation of work at congresses

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    Interference rejection by taking advantage of the radiation pattern diversity of a reconfigurable antenna is considered. It is proposed to use simultaneously frequency and radiation reconfiguration to extend interference rejection capabilities to large bandwidths. A small-size low-complexity pixel antenna is used to provide interference rejection capabilities over an octave bandwidth. An average signal-to-interference ratio of 24 dB is achieved and interference rejections above 15 dB are reliably provided over the whole frequency bandwidth and an angular range of 120o

  • MM-wave scattering measurements for imaging and channel characterization

     Toda, A.P.; de Flaviis, Franco; Jofre Roca, Luis; Romeu Robert, Jordi
    European Conference on Antennas and Propagation
    Presentation's date: 2012
    Presentation of work at congresses

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    In this paper, mm-wave band scattering measurements are performed and imaging reconstructions obtained using a 2-D Scatterer Mapping Technique based on a Multi-Frequency Bi-Focusing operator (MF-BF). The measured data matrix is also processed to obtain its eigenvalues and eigenvectors. A relation between the eigenvalues and the number of scatterers and the eigenvectors and the scatterers spatial localization is obtained.

    In this paper, mm-wave band scattering measurements are performed and imaging reconstructions obtained using a 2-D Scatterer Mapping Technique based on a Multi-Frequency Bi-Focusing operator (MF-BF). The measured data matrix is also processed to obtain its eigenvalues and eigenvectors. A relation between the eigenvalues and the number of scatterers and the eigenvectors and the scatterers spatial localization is obtained.

  • UWB Magnitude combined realistic breast model imaging capabilities

     Guardiola, Marta; Jofre Roca, Luis; Romeu Robert, Jordi
    IEEE International Symposium on Antennas and Propagation
    Presentation's date: 2012-07
    Presentation of work at congresses

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    Breast cancer is the leading cancer killer among women. Early stage detection has been recognized to be best solution to reduce mortality rates. A non-ionizing, economical screening system based on microwave imaging is being investigated, but it is still a long way towards clinical ready system. In this paper, the validation of UWB-MC tomographic algorithm is performed using realistic breast models.

  • Input impedance measurements of cell phone antennas using backscattering modulation

     Monsalve, Beatriz; Blanch Boris, Sebastian; Romeu Robert, Jordi
    European Conference on Antennas and Propagation
    Presentation's date: 2012-04
    Presentation of work at congresses

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    This contribution presents an overview of the backscattering modulation applied to input impedance measurements of cell phone antennas.

  • Optical cross-correlation of millimeter wave signals applied to interferometric radiometry

     Nova, Enrique; Romeu Robert, Jordi; Torres Torres, Francisco; Broquetas Ibars, Antoni; Jofre Roca, Luis
    International Conference on Infrared, Millimeter, and Terahertz Waves
    Presentation's date: 2012-07
    Presentation of work at congresses

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    This paper presents a method to perform in the opti- cal domain the correlations required when processing millimeter wave interferometric radiometer signals. The main problem when addressing the design of an interferometric radiometer working at W-band resides on the distribution and correlation of large bandwidth signals acquired by each radiometer receiver. In order to avoid the necessity of baseband processing of signals with large relative bandwidths, the signals coming from the radiometric receivers are up-converted to the optical domain using LiNbO3 optical phase modulators. The modulated signals from each receiver pairs are added and and detected by a photodiode. The correlation is obtained from the resulting photocurrent.

  • Retina design for 100GHz MST imaging system

     Alonso, Maria; Garg, V.; Nova, Enrique; Abril, Jordi; Romeu Robert, Jordi; Llombart, Núria; Jofre Roca, Luis
    IEEE International Symposium on Antennas and Propagation
    Presentation's date: 2012-07
    Presentation of work at congresses

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    A near field imaging system for THz tomographic imaging based on a MST retina (an array of real antennas) has been designed. The main adva ntage of this implementation is the absence of microwave transmission line distribution networks and the capability to perform high speed imaging. The aim of this paper is to describe the design of the retina in order to maximize the performance of this im aging system.

  • Tomographic imaging retina at 100 GHz

     Alonso, Maria; Garg, V; Romeu Robert, Jordi; Llombart, Núria; Jofre Roca, Luis
    International Conference on Infrared, Millimeter, and Terahertz Waves
    Presentation's date: 2012-09
    Presentation of work at congresses

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    This paper presents a tomographic system at 100 GHz for imaging based on MST technique. At 100 GHz, a good compromise is obtained between penetration and reso- lution for biomedical and non-destructive testing applications. Moreover, this system just requires low frequency wiring and reduces the RF equipment necessary for performing real-time imaging. The system has been built and successfully validated with a set of measurements for a canonical scenario.

  • Water infiltration detection in civil engineering structures using RFID

     Capdevila Cascante, Santiago; Roqueta Crusats, Gemma; Guardiola Garcia, Marta; Jofre Roca, Luis; Romeu Robert, Jordi; Bolomey, Jean Charles
    European Conference on Antennas and Propagation
    Presentation's date: 2012
    Presentation of work at congresses

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  • UWB brain differential imaging capabilities

     Guardiola Garcia, Marta; Jofre Roca, Luis; Capdevila Cascante, Santiago; Romeu Robert, Jordi
    European Conference on Antennas and Propagation
    Presentation's date: 2012
    Presentation of work at congresses

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  • Real time 100 GHz MST imaging retina

     Alonso Del Pino, Maria; Garg, V.; Garcia Guerra, Carlos Enrique; Romeu Robert, Jordi; Llombart, Núria; Jofre Roca, Luis
    European Conference on Antennas and Propagation
    Presentation's date: 2012-03-26
    Presentation of work at congresses

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    A real time tomographic imaging system at 100 GHz based on a retina and Modulated Scattered Technique (MST) is presented in this paper. It consists in applying a low frequency modulation to each probe of an array of antennas in order to coherently detect the electric field by a collector. This system just requires low frequency wiring and reduces the RF equipment necessary for each pixel for a planar surface. The aim of this paper is to analyze the performance of different tomographic imaging processes for the imaging system described.

    A real time tomographic imaging system at 100 GHz based on a retina and Modulated Scattered Technique (MST) is presented in this paper. It consists in applying a low frequency modulation to each probe of an array of antennas in order to coherently detect the electric field by a collector. This system just requires low frequency wiring and reduces the RF equipment necessary for each pixel for a planar surface. The aim of this paper is to analyze the performance of different tomographic imaging processes for the imaging system described.

  • Assessment of the performance of a metamaterial spacer in a closely spaced multiple-antenna system

     Imbert, Marc; Ferrer, P. J.; González Arbesú, José María; Romeu Robert, Jordi
    IEEE antennas and wireless propagation letters
    Date of publication: 2012
    Journal article

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  • 3-D microwave magnitude combined tomography for breast cancer detection using realistic breast models

     Guardiola Garcia, Marta; Capdevila Cascante, Santiago; Romeu Robert, Jordi; Jofre Roca, Luis
    IEEE antennas and wireless propagation letters
    Date of publication: 2012
    Journal article

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  • Efficient parametric characterization of the dynamic performance of an RFID IC

     Capdevila Cascante, Santiago; Jofre Roca, Luis; Romeu Robert, Jordi; Bolomey, Jean Charles
    IEEE microwave and wireless components letters
    Date of publication: 2012
    Journal article

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    In this letter, a measurement technique for a complete parametric characterization of the input impedance of an RFID IC is presented. The use of an SPDT switch to modulate the signal from the network analyzer provides the capability to measure the RFID IC activation level and its input impedance simultaneously. This data can then be used to fully predict the dynamic response and performance of an RFID tag.

  • Microwave Propagative Imaging for Nondestructive Evaluation of Concrete Structures

     Roqueta Crusats, Gemma
    Defense's date: 2012-07-19
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • IEEE Fellow

     Romeu Robert, Jordi
    Award or recognition

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  • Atmospheric propagation at 100 and 300 GHz: assessment of a method to identify rainy conditions during radiosoundings

     Siles, G.A.; Riera, J.M.; Garcia del Pino, P; Romeu Robert, Jordi
    Progress in electromagnetics research (PIER)
    Date of publication: 2012
    Journal article

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  • Fabrication and measurement of homemade standard antennas

     Guardiola Garcia, Marta; Monsalve Carcelen, Beatriz; Calafell Rueda, Irena; Roqueta Crusats, Gemma; Romeu Robert, Jordi
    IEEE antennas and propagation magazine
    Date of publication: 2012
    Journal article

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    Apprenticeship is linked to training. This paper is intended to be a tutorial on how to design, fabricate, and measure antennas in an economical and easy way, using recycled materials and common electronic devices such as a laptop and an access point. Several antenna designs built with household materials are proposed, giving practical design and fabrication guidelines. The use of the Wi-Fi band allows linking the experiment with daily-life devices, and proposing a simple and economical antenna-measurement system. The capacity to experiment with antennas from their design to measurement will defi nitely stimulate undergraduate or graduate students to get acquainted with the basic topics of antennas and propagation. The paper presented herein was awarded with the fi rst price in the IEEE AP-S Student Challenge 2010 [1, 2].

  • Interlaced multiband antenna arrays

     Puente Baliarda, Carles; Romeu Robert, Jordi; Blanch Boris, Sebastian
    Date of request: 2012-06-22
    Invention patent

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  • Correlador para múltiples receptores de señal de radiofrecuencia implementado con tecnología óptica

     Nova Lavado, Enrique; Romeu Robert, Jordi
    Date of request: 2012-10-17
    Invention patent

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  • Micrometric deformation imaging at W-Band

     Abril, Jordi; Nova, Enrique; Broquetas Ibars, Antoni; Aguasca Sole, Alberto; Romeu Robert, Jordi; Jofre Roca, Luis
    IEEE International Microwave Workshop
    Presentation's date: 2011-08-24
    Presentation of work at congresses

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    The measurement of scattered signals at W Band can be exploited to form images of small deformations with precisions in the order of tenths of micrometers. In this paper an Interferometric Synthetic Aperture Radar setup is proposed to form high resolution reflectivity images and deformation maps of dielectric or metallic surfaces. First, the system geometry of observation based on a linear motion of the radar antennas is described. A CW frequency domain measurement provides the wide band required for high resolution imaging. The scattered field data is focused on the surface spatial domain using a combination of range compression based on Inverse Fourier Transform combined with a backprojection algorithm to form the synthetic aperture with a high cross range resolution. The focusing performance has been assessed by numerical simulations and experimental measurements of simple scattering objects like spheres and trihedrals. Interferometric images of controlled displacements have been obtained showing a good agreement between real and measured displacements. A representative surface deformation test has been also carried out using a metallic rough surface. The interferometric phase difference between acquisitions can be used to image local deformations in the order of tens of micrometers from a range of several meters. Likewise the interferogram coherence shows the degree of decorrelation of the radar reflectivity which provides valuable information for surface random change assessment.

  • The ¿challenging¿ world of Terahertz radiation and imaging

     Jofre Roca, Luis; Romeu Robert, Jordi; Capdevila, Santiago; Abril, Jordi; Nova, Enrique; Alonso, Maria
    European Conference on Antennas and Propagation
    Presentation's date: 2011-04-15
    Presentation of work at congresses

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    THz propagation through materials may reveal unique macroscopic and physical properties of their internal structure without the damage associated with ionizing radiation. The generation, radiation, and detection of THz signals relays into an intermediate region between microwave and optical frequencies seen as a transition in device physics from classical transport to quantum transition. The physical properties and parameters of the antennas and electronic devices at these frequencies (0.1-10THz) will we compared with their microwave and optical counterparts, the important differences highlighted and its significance in terms of spectral bandwidth and signal-to-noise ratio for near and short range imaging systems reviewed. Finally, some of the recent significant developments in the field will be summarized and the potential applications and future challenges and opportunities identified.

  • Antenna reconfigurability based on a novel parasitic pixel layer

     Rodrigo Lopez, Daniel; Damgaci, Yasin; Unlu, M.; Cetiner, Bedri Artug; Romeu Robert, Jordi; Jofre Roca, Luis
    European Conference on Antennas and Propagation
    Presentation's date: 2011-04
    Presentation of work at congresses

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    A novel reconfiguration method based in the use of pixel surfaces as parasitic elements is presented. This concept can be used to provide reconfigurability to a wide variety of non-reconfigurable antennas without requiring additional modifications on the basic antenna design and avoiding any physical interconnections. General guidelines are provided for the design of parasitic pixel surfaces. Reconfigurability of a parasitic pixel layer used in conjunction with a patch antenna is analyzed. Results demonstrate simultaneous frequency and radiation pattern reconfiguration with capabibity of providing till a 10% frequency tuning range and beamsteering over 30º.

  • 100 GHz retina for THz tomographic imaging

     Maria, Alonso; Guerra, C; Nova, Enrique; Abril, Jordi; Romeu Robert, Jordi; Llombart, Núria; Jofre Roca, Luis
    International Conference on Infrared, Millimeter, and Terahertz Waves
    Presentation's date: 2011-10-07
    Presentation of work at congresses

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    In a tomographic imaging system, the key is to collect a sufficient number of scattered field points to recover the currents in the inverse scattering problem. This can be accomplished by using a real array of multiplexed antennas for real time imaging. In this paper, a W-Band Retina for Terahertz tomographic imaging is presented. A system based on a retina, a collector and an illuminator is described and the results of a fabricated retina are shown.

  • W-band radiometric imager with mechanical beam-scanning

     Nova, Enrique; Abril, Jordi; Romeu Robert, Jordi; Broquetas Ibars, Antoni; Torres Torres, Francisco; Jofre Roca, Luis
    International Conference on Infrared, Millimeter, and Terahertz Waves
    Presentation's date: 2011-10-02
    Presentation of work at congresses

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    The design of a 94 GHz Total Power Radiometer system for imaging purposes is presented in this paper. A mechanical beam-scanning antenna system is used to acquire passive raster images. The main performance parameters of the imaging system are described as well as their impact on the resulting image quality. A temperature resolution below 1K and a spatial resolution around 4 cm at 1 meter standoff distance are obtained with this system. Moreover, radiometric images acquired in indoor and outdoor environments are shown and compared.

  • Characterization of a 94 GHz radiometric imager with mechanical beam-scanning

     Nova, Enrique; Abril, Jordi; Romeu Robert, Jordi; Broquetas Ibars, Antoni; Torres Torres, Francisco; Jofre Roca, Luis
    IEEE International Microwave Workshop
    Presentation's date: 2011-08-24
    Presentation of work at congresses

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    This paper presents the characterization in terms of spatial resolution and radiometric sensitivity of a W-band Total Power Radiometer (TPR). The TPR is based on a heterodyne receiver with 64 dB of gain and 6.5 dB of noise figure. An antenna system consisting on a pan-tilt scanner has been designed and built in order to aim a 100 mm offset parabolic reflector. With this system, relative temperature images of targets at a 1 m standoff range are obtained in indoor environments with an spatial resolution of 4 cm.

  • Passive RFID based sensing

     Capdevila, Santiago; Jofre Roca, Luis; Romeu Robert, Jordi; Bolomey, Jean Charles
    IEEE International Conference on RFID-Technologies and Applications
    Presentation's date: 2011-11-16
    Presentation of work at congresses

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    The principle of communication of passive RFID, which relies on the Modulated Scattering Technique (MST) to transmit the information from the tag to the reader, opens a way to enable conventional RFID for sensing purposes, without any additional circuitry. In this paper a short description of the physical principle behind the sensing is presented along with measurements of RFID tags used for sensing in multiple applications, such as electromagnetic field measurement temperature or presence detection.

  • Deforming and relief interferometric SAR imaging at W-band

     Abril, Jordi; Nova, Enrique; Broquetas Ibars, Antoni; Aguasca Sole, Alberto; Romeu Robert, Jordi; Jofre Roca, Luis
    International Conference on Infrared, Millimeter, and Terahertz Waves
    Presentation's date: 2011-10-02
    Presentation of work at congresses

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    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 in which the scattered field is focused using a combination of range compression and backpropagation algorithm. Interferometric images involving micrometric displacements have been obtained showing a good agreement between real and measured displacements. A metallic rough surface deformation test has been first performed, by imaging the phase difference between acquisitions before and after the displacement. The interferometric phase difference between acquisitions can be used to image local deformations from a range of several meters. Furthermore the interferogram coherence shows the degree of decorrelation of the radar reflectivity which provides valuable information for surface random change. Likewise the relief of the surface with an L-shape target is retrieved mapping the phase difference between the two receiving antennas, in this case an static scenario is required.

  • Transpolarizing trihedral corner reflector characterization using a GB-SAR system

     Ferrer, Pere J.; López Martínez, Carlos; Aguasca Sole, Alberto; Pipia, Luca; González Arbesú, José María; Fabregas Canovas, Francisco Javier; Romeu Robert, Jordi
    IEEE Geoscience and Remote Sensing Letters
    Date of publication: 2011-07
    Journal article

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    The use of a low-profile, lightweight, and easy-to-fabricate transpolarizing surface placed on one side of a trihedral corner reflector (TCR) as a polarimetric calibrator is presented in this letter. The transpolarizing TCR presents a high backscattered cross-polar response contrary to standard TCRs. The performance of this device has been tested at the X-band using the Universitat Politecnica de Catalunya ground-based synthetic aperture radar.

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    Digital portfolio for learning: A new communication channel for education  Open access

     Coromina, Judit; Sabate Garriga, Ferran; Romeu Robert, Jordi; Ruiz, Ferran
    Intangible capital
    Date of publication: 2011
    Journal article

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    Propósito: La Generalitat de Catalunya tiene previsto introducir antes del año 2017 el portafolio digital, una iniciativa vinculada con los nuevos métodos de aprendizaje. Constatado el creciente interés por el portafolio digital como medio de comunicación en la educación, este artículo tiene por objetivos describir detalladamente su funcionamiento e identificar una lista de criterios, útiles a los centros educativos, para seleccionar la aplicación de gestión del portafolio digital que mejor se adapte a sus necesidades. Diseño/metodología/enfoque: En primer lugar se fija el marco teórico de funcionamiento del portafolio digital. Luego se tipifican las aplicaciones que son usadas comúnmente para su implementación. A continuación se realiza un análisis de requisitos de una aplicación ideal con acuerdo a las fases de creación del portafolio identificados en el marco teórico. Finalmente, a partir de estos requisitos se identifica una lista de criterios útiles para seleccionar la aplicación de soporte al portafolio. Resultados y originalidad/valor: El artículo aporta un proceso estructurado en etapas y fases para la creación del portafolio digital que va más allá de los existentes en la literatura. Además, define una lista de criterios útiles para seleccionar la aplicación de soporte al portafolio digital Portafolio digital de aprendizaje: Un nuevo medio de comunicación en la educación 117 J. Coromina, F. Sabate, J. Romeu, F. Ruiz que más convenga a un centro educativo, obtenidos con una metodología bastante exhaustiva. Limitaciones/implicaciones de investigación: Para poner en práctica los criterios identificados se propone completar, en un nuevo estudio, el modelo de decisión multicriterio, especificando los procesos para pesar los criterios y normalizarlos. Después se podría analizar la validez del modelo estudiando la satisfacción obtenida por su uso en una muestra de centros educativos. Implicaciones prácticas: La lista de criterios se espera facilite la selección de la aplicación informática de soporte al portafolio de aprendizaje a los centros educativos, con acuerdo a sus necesidades específicas.

  • Portafolio digital de aprendizaje: un nuevo medio de comunicación en la educación

     Coromina, Judit; Sabate Garriga, Ferran; Romeu Robert, Jordi; Ruiz, Ferran
    Intangible capital
    Date of publication: 2011
    Journal article

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  • ELECTROMAGNETIC PROPAGATION IN TUNNELS  Open access

     Izquierdo Fernández, Benjamín
    Defense's date: 2011-09-22
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    Introduction of wireless communications systems in railway communications are at the origin of this thesis. Ifercat, the company in charge of the development of Línia 9 of Barcelona Metro, decided that wireless systems were employed in order to increase efficiency and safety. For this reason, characterisation of ISM 5.8GHz band in tunnel environments for broad band wireless train communications becomes necessary. Tunnel environments constitute harsh environments due to humidity, obstacles, power systems, moving trains, curves¿ The Automatic Train Control system requires a 20MHz bandwidth for train-to-ground video transmission in order to get on-board information and surveillance. Given that Línia 9 was at the early stages of its development at the beginning of the study, a dual-polarised spectral simulator was developed first. Spectral techniques work in both spatial and spatial-frequency domain and are extremely adaptable to changes in the tunnel cross section as the wave front passes down the tunnel. Efficiency of this technique comes from the well-known properties of FFT algorithms. Spectral techniques provide good near-field predictions and can model different antenna configurations easily. On the other hand, boundary conditions present some issues that must be overcome. Long tunnels also represent a problem in terms of required memory space. The parabolic equation has been used to enhance the performance of spectral techniques far from the source. They complement each other well because parabolic conditions require smooth variations in one direction, thus far from the source, where only field components propagating parallel to the tunnel axis remain, in order to provide accurate results. Application of Leontovich boundary conditions ensures proper solution at the change of media and its low computational cost permits acceleration of predictions. These two techniques are then combined to verify the measurement campaigns developed at metro tunnels during the thesis. MIMO schemes are used to enhance the system throughput and simulation predictions are compared to measurements with good results. The work presented in this thesis consisted first on implementing both simulators and verifying their correct behaviour with theoretical analytical solutions. Secondly, predictions are compared with measurement campaigns carried out in Barcelona Metro environments. The study focuses on EM attenuation, field distribution, fading characterisation, antenna location and MIMO processing at the frequency band of interest.

  • INTEGRATED RADIANT SYSTEMS DESIGN FOR WIRELESS SENSORS

     Serrano Calvo, Raquel
    Defense's date: 2011-07-22
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • DESIGN AND CHARACTERIZATION TECHNIQUES FOR EMBEDDED ANTENNAS USING NOVEL MATERIALS

     Monsalve Carcelén, Beatriz
    Defense's date: 2011-12-01
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • Multi-element arrays in subway environments

     Alonso Valdesueiro, Javier
    Defense's date: 2011-02-02
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • Radiation pattern reconfigurable microfabricated planar millimeter-wave antennas  Open access

     Balcells Ventura, Jordi
    Defense's date: 2011-05-20
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    Els serveis de telecomunicacions i sistemes radar estan migrant a freqüències mil•limètriques (MMW), on es disposa d 'una major amplada de banda i conseqüentment d'una major velocitat de transmissió de dades. Aquesta migració requereix de l'ús de diferents tecnologies amb capacitat d'operar a la banda de freqüències mil•limètriques (30 a 300 Ghz), i més concretament en les bandes Ka (26,5 - 40GHz), V (50 – 75GHz) i W (75 – 110GHz). En moltes aplicacions i sobretot en aquelles on l'antena forma part d'un dispositiu mòbil, es cerca poder utilitzar antenes planes, caracteritzades per tenir unes dimensions reduïdes i un baix cost de fabricació. El conjunt de requeriments es pot resumir en obtenir una antena amb capacitat de reconfigurabilitat i amb un baix nivell de pèrdues en cada una de les bandes de freqüència. Per tal d'afrontar aquests reptes, les dimensions de les antenes mil•limètriques, juntament amb els tipus de materials, toleràncies de fabricació i la capacitat de reconfigurabilitat ens porten a l'ús de processos de microfabricació. L'objectiu d'aquesta tesis doctoral és l'anàlisi dels conceptes mencionats, tipus de materials, geometries de línia de transmissió i interruptors, en el context de les freqüències mil•limètriques, així com la seva aplicació final en dissenys d'antenes compatibles amb els processos de microfabricació. Finalment, com a demostració s'han presentat dissenys específics utilitzables en tres aplicacions a freqüències mil•limètriques: Sistemes de Comunicació per Satèl•lit (SCS) a la banda Ka, Xarxes d'àrea personal inalàmbriques (WPAN) a la banda V i sistemes radar per l'automoció a la banda W. La primera part d'aquesta tesis consisteix en l'anàlisi d'algunes tecnologies circuitals a freqüències mil•limètriques. S'han presentat els materials més utilitzats a altes freqüències (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) i Low Temperature Co-fired Ceramic (LTCC)) i s'han comparat en termes de permitivitat i tangent de pèrdues. També s'inclou un estudi de pèrdues a altes freqüències en les principals línies de transmissió (microstrip, stripline i CPW). Finalment, es presenta un resum dels interruptors RF-MEMS i es comparen amb els PIN diodes i els FET. En la segona part, es presenten diferents agrupacions d'antenes amb la capacitat de reconfigurar la polarització i la direcció d'apuntament. S'han dissenyat dos elements base reconfigurables en polarització: CPW Patch antena i 4-Qdime antena. La primera antena consisteix en un element singular amb interruptors RF-MEMS, dissenyada per operar a les bandes Ka i V. La segona antena consisteix en una arquitectura composta on la reconfigurabilitat en polarització s'obté mitjançant variant la fase d'alimentació de cada un dels quatre elements lineals. La fase és controlada mitjançant interruptors RF-MEMS ubicats en la xarxa de distribució. L'antena 4-Qdime s'ha dissenyat per operar en les bandes V i W. Ambdós elements base s'han utilitzat posteriorment pel disseny de dues agrupacions d'antenes amb capacitat de reconfigurar l'apuntament del feix principal. La reconfigurabilitat es dur a terme utilitzant desfasadors de fase d'1 bit. La part final de la tesis es centra en les toleràncies de fabricació i en els processo de microfabricació d'agrupacions d'antenes mil•limètriques. Les toleràncies de fabricació s'han estudiat en funció dels error d'amplitud i fase en cada element de l'agrupació, fixant-se en les pèrdues de guany, error d'apuntament, error en l'amplada de feix, errors en el nivell de lòbul secundari i en l'error en la relació axial. El procés de microfabricació de les diferents antenes dissenyades es presenta en detall. Els dissenys de l'antena CPW Patch reconfigurable en polarització i apuntament operant a les bandes Ka i V, s'han fabricat en la sala blanca del Cornell NanoScale Science & Technology Facility (CNF). Posteriorment, s'han caracteritzat l'aïllament i el temps de resposta dels interruptors RF-MEMS, i finalment, el coeficient de reflexió, el diagrama de radiació i la relació axial s'han mesurat a les bandes Ka i V per les antenes configurades en polarització lineal (LP) i circular (CP).

    Telecommunication services and radar systems are migrating to Millimeter-wave (MMW) frequencies, where wider bandwidths are available. Such migration requires the use of different technologies with the capability to operate at the MMW frequency band (30 to 300GHz), and more specifically at Ka- (26.5 to 40GHz), V- (50 to 75GHz) and W-band (75 to 110GHz). For many applications and more concretely those where the antenna is part of a mobile device, it is targeted the use of planar antennas for their low profile and low fabrication cost. A wide variety of requirements is translated into a reconfiguration capability and low losses within each application frequency bandwidth. To deal with the mentioned challenges, the MMW antenna dimensions, together with the materials, fabrication tolerances and reconfigurability capability lead to microfabrication processes. The aim of this thesis is the analysis of the mentioned concepts, materials, transmission lines geometries and switches in the MMW frequencies context and their final application in antenna designs compatible with microfabrication. Finally, specific designs are presented as a demonstration for three MMW applications: Satellite Communication Systems (SCS) at Ka-band, Wireless Personal Area Network (WPAN) at V-band and Automotive Radar at W-band. The first part of this thesis consist to analyze some MMW circuit technologies. The four most used materials at MMW frequencies (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) and Low Temperature Co-fired Ceramic (LTCC)) have been presented and compared in terms of permittivity (εr) and loss tangent (tanδ). An study of the main transmission lines attenuation (microstrip, stripline and CPW) at high frequencies is included. Finally, an overview of the RF-MEMS switches is presented in comparison with PIN diodes and FETS switches. The second part presents different polarization and beam pointing reconfigurable array antennas. Two polarization-reconfigurable base-elements have been designed: CPW Patch antenna and 4-Qdime antenna. The first consists of a single reconfigurable element with integrated RF-MEMS switches, designed to operate at Ka- and V-band. The second antenna presented in this thesis has a composed architecture where the polarization reconfigurability is obtained by switching the phase feeding for each of the four linear polarized elements in the feed network with RF-MEMS switches. The 4-Qdime antenna has been designed to operate at V- and W-band. The two base-elements have been used to design two beam pointing reconfigurable antenna arrays. Using phased array techniques, beamsteering is computed and implemented with 1-bit discrete phase-shifter. The final part of the thesis is focused into the fabrication tolerances and microfabrication process of Millimeter-wave antenna arrays. The fabrication tolerances have been studied as a function of the amplitude and phase errors presented at each elements array, focusing on the gain loss, beam pointing error, Half-Power Beamwidth (HPBW) error, sidelobe level error and axial ratio error. The microfabrication process for the designed antennas is presented in detail. Polarization- and pointing- reconfigurable CPW Patch antenna operating at Ka- and V- band have been fabricated in a clean-room facility at Cornell NanoScale Science & Technology Facility (CNF). The RF-MEMS switches isolation and time response have been characterized. Finally, the reflection coefficient, radiation pattern and axial ratio have been measured at Ka- and V-band for the fabricated antennas configured in Linear Polarization (LP) and Circular Polarization (CP).

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    Aprendizaje y asistencia virtual en red /Aprenentatge i assistència virtual en xarxa  Open access

     Jofre Roca, Luis; Romeu Robert, Jordi; Vallverdu Bayes, Francisco; Fuentes Fort, Maria; Guardiola Garcia, Marta; Gonzalez Bermudez, Meritxell
    Date of publication: 2011-01
    Book

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  • Design, simulation and measurement of millimetre wave antennas for comunications and imaging

     Blanch Boris, Sebastian; Cardama Aznar, Angel; Jofre Roca, Luis; Romeu Robert, Jordi; Roqueta Crusats, Gemma; Guardiola Garcia, Marta; Serrano Calvo, Raquel; Izquierdo Fernandez, Benjamin; Alonso Valdesueiro, Javier; Capdevila Cascante, Santiago; Monsalve Carcelen, Beatriz; Diaz Tapia, Edgar; Rodrigo Lopez, Daniel; Nova Lavado, Enrique; Rius Casals, Juan-manuel
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  • Aprendizaje y asistencia virtual en red. La prueba Piloto.

     Fuentes Fort, Maria; Gonzalez Bermudez, Meritxell; Guardiola Garcia, Marta; Jofre Roca, Luis; Romeu Robert, Jordi; Vallverdu Bayes, Francisco
    Date: 2011-07-29
    Report

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