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  • New graphical processing technique for fast shadowing computation in PO surface integral

     Rius Casals, Juan-manuel; Carbo Meseguer, Alexis; Bjerkemo, Jakob; Ubeda Farre, Eduardo; Heldring, Alexander; Mallorqui Franquet, Jordi Joan; Broquetas Ibars, Antoni
    IEEE transactions on antennas and propagation
    Vol. 62, num. 5, p. 2587-2595
    DOI: 10.1109/TAP.2014.2307321
    Date of publication: 2014-05-01
    Journal article

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    This paper presents a new graphical processing technique for fast computation of PO surface integral. In contrast with the original graphical processing approach introduced by the authors in 1993, the new one combines a novel shadowing computation algorithm together with the conventional facet-based Gordon's formula, instead of the pixel-based Asvestas' approximation. The resulting hybrid approach needs more CPU power for very complex radar targets, but is free from the pixel discretization noise inherent to graphical processing. It has the same accuracy as conventional Physical Optics computation, but shadowed facets detection is more than 10 times faster than with the most efficient alternative algorithms of O(N log N) computational cost. © 2014 IEEE.

    This paper presents a new graphical processing technique for fast computation of PO surface integral. In contrast with the original graphical processing approach introduced by the authors in 1993, the new one combines a novel shadowing computation algorithm together with the conventional facet-based Gordon's formula, instead of the pixel-based Asvestas' approximation. The resulting hybrid approach needs more CPU power for very complex radar targets, but is free from the pixel discretization noise inherent to graphical processing. It has the same accuracy as conventional Physical Optics computation, but shadowed facets detection is more than 10 times faster than with the most efficient alternative algorithms of O(N log N) computational cost. © 2014 IEEE.

  • Bistatic geosynchronous SAR for land and atmosphere continuous observation

     Ruiz Rodon, Josep; Broquetas Ibars, Antoni; Monti Guarnieri, Andrea; Recchia, Andrea
    European Conference on Synthetic Aperture Radar
    p. 280-283
    Presentation's date: 2014-06-05
    Presentation of work at congresses

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    In this paper the bistatic SAR observation from low-eccentric nearly zero inclined geosynchronous orbits (GEOSAR) is studied. Two operation frequencies have been analysed with different compromises between spatial resolution and acquisition time. The impact of the orbital design in the final SAR radiometric and spatial resolution performance is assessed allowing assessment of appropriate spatial resolution and coverage compromises.

    In this paper the bistatic SAR observation from low-eccentric nearly zero inclined geosynchronous orbits (GEOSAR) is studied. Two operation frequencies have been analysed with different compromises between spatial resolution and acquisition time. The impact of the orbital design in the final SAR radiometric and spatial resolution performance is assessed allowing assessment of appropriate spatial resolution and coverage compromises.

  • Fast simulation performance evaluation of spaceborne SAR-GMTI missions for maritime applications

     Makhoul Varona, Eduardo; Zhan, Yu; Ceba Vega, Francisco; Broquetas Ibars, Antoni; Beaton, Alasdhair; Letterio, Federico; Tonetti, Stefania; Barbarossa, Sergio; di Lorenzo, Paolo; Maffei, Marco
    European Conference on Synthetic Aperture Radar
    p. 682-685
    Presentation's date: 2014-06-04
    Presentation of work at congresses

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    This paper presents a flexible simulator for Ground Moving Target Indication (GMTI) in the frame of spaceborne Synthetic Aperture Radar (SAR) over maritime scenarios. The simulation tool provides GMTI performance metric in terms of probability of detection, extracted from an off-line database generated through intensive Monte Carlo (MC) simulations, overlaid on top of synthetic SAR-GMTI processed images. Different system configurations have been evaluated considering Along-Track Interferometry (ATI), Displaced Phase Center Antenna (DPCA) and Extended DPCA (EDPCA) GMTI techniques

    This paper presents a flexible simulator for Ground Moving Target Indication (GMTI) in the frame of spaceborne Synthetic Aperture Radar (SAR) over maritime scenarios. The simulation tool provides GMTI performance metric in terms of probability of detection, extracted from an off-line database generated through intensive Monte Carlo (MC) simulations, overlaid on top of synthetic SAR-GMTI processed images. Different system configurations have been evaluated considering Along-Track Interferometry (ATI), Displaced Phase Center Antenna (DPCA) and Extended DPCA (EDPCA) GMTI techniques

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

     Nova Lavado, Enrique; Romeu Robert, Jordi; Torres Torres, Francisco; Pablos Hernandez, Miriam; Riera Salis, José Manuel; Broquetas Ibars, Antoni; Jofre Roca, Luis
    IEEE transactions on geoscience and remote sensing
    Vol. 51, num. 4, p. 2327-2336
    DOI: 10.1109/TGRS.2012.2211025
    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.

    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.

  • Geosynchronous SAR focusing with atmospheric phase screen retrieval and compensation

     Ruiz Rodon, Josep; Broquetas Ibars, Antoni; Monti Guerneri, Andrea; Rocca, Fabio
    IEEE transactions on geoscience and remote sensing
    Vol. 51, num. 8, p. 4397-4404
    DOI: 10.1109/TGRS.2013.2242202
    Date of publication: 2013
    Journal article

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    In this paper, a geosynchronous synthetic aperture radar (SAR) (GEOSAR) mission for atmospheric phase screen (APS) retrieval using a long coherent integration of pulses is analyzed. The nearly fixed position of the geosynchronous platforms makes GEOSAR systems suitable for continuous monitoring applications. However, using moderate transmitted powers and antenna sizes, very long integration times up to hours are required. In GEOSAR, the two-way propagation of radar signals can decorrelate significantly due to atmospheric changes during the long data take, resulting in an APS which can cause image defocusing and artifacts. In this paper, the APS effects are analyzed, and an APS correction algorithm from short-term periodic acquisitions (subapertures) of the whole long-term GEOSAR synthetic aperture is described. The results obtained from the APS retrieval algorithm in a simulated GEOSAR acquisition affected by atmospheric decorrelation are presented. Finally, an experimental test of the APS algorithm performance with a long-integration ground-based SAR acquisition is shown.

    In this paper, a geosynchronous synthetic aperture radar (SAR) (GEOSAR) mission for atmospheric phase screen (APS) retrieval using a long coherent integration of pulses is analyzed. The nearly fixed position of the geosynchronous platforms makes GEOSAR systems suitable for continuous monitoring applications. However, using moderate transmitted powers and antenna sizes, very long integration times up to hours are required. In GEOSAR, the two-way propagation of radar signals can decorrelate significantly due to atmospheric changes during the long data take, resulting in an APS which can cause image defocusing and artifacts. In this paper, the APS effects are analyzed, and an APS correction algorithm from short-term periodic acquisitions (subapertures) of the whole long-term GEOSAR synthetic aperture is described. The results obtained from the APS retrieval algorithm in a simulated GEOSAR acquisition affected by atmospheric decorrelation are presented. Finally, an experimental test of the APS algorithm performance with a long-integration ground-based SAR acquisition is shown.

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    ARBRES: Light-weight CW/FM SAR sensors for small UAVs  Open access

     Aguasca Sole, Alberto; Acevo Herrera, René; Broquetas Ibars, Antoni; Mallorqui Franquet, Jordi Joan; Fabregas Canovas, Francisco Javier
    Sensors
    Vol. 13, num. 3, p. 3204-3216
    DOI: 10.3390/s130303204
    Date of publication: 2013-03-06
    Journal article

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    This paper describes a pair of compact CW/FM airborne SAR systems for small UAV-based operation (wingspan of 3.5 m) for low-cost testing of innovative SAR concepts. Two different SAR instruments, using the C and X bands, have been developed in the context of the ARBRES project, each of them achieving a payload weight below 5 Kg and a volume of 13.5 dm3 (sensor and controller). Every system has a dual receiving channel which allows operation in interferometric or polarimetric modes. Planar printed array antennas are used in both sensors for easy system integration and better isolation between transmitter and receiver subsystems. First experimental tests on board a 3.2 m wingspan commercial radio-controlled aircraft are presented. The SAR images of a field close to an urban area have been focused using a back-projection algorithm. Using the dual channel capability, a single pass interferogram and Digital Elevation Model (DEM) has been obtained which agrees with the scene topography. A simple Motion Compensation (MoCo) module, based on the information from an Inertial+GPS unit, has been included to compensate platform motion errors with respect to the nominal straight trajectory.

  • An efficient method for the azimuth compression of geosynchronous SAR data through sub-apertures processing

     Belotti, Michele; Broquetas Ibars, Antoni; Leanza, Antonio; Monti Guarnieri, Andrea; Recchia, Andrea; Rocca, Fabio; Ruiz Rodon, Josep; Tebaldini, Stefano
    IEEE International Geoscience and Remote Sensing Symposium
    p. 2047-2050
    DOI: 10.1109/IGARSS.2013.6723213
    Presentation's date: 2013-07-21
    Presentation of work at congresses

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    We propose an efficient method for the azimuth compression and Atmospheric Phase Screen estimation of Geosynchronous SAR data. The method is based on the iterative processing of sub-apertures of increasing size, allowing to gradually refine the quality of the focused data and of the estimated APS. The whole processing can be easily parallelized. Results over simulated data are shown. © 2013 IEEE.

    We propose an efficient method for the azimuth compression and Atmospheric Phase Screen estimation of Geosynchronous SAR data. The method is based on the iterative processing of sub-apertures of increasing size, allowing to gradually refine the quality of the focused data and of the estimated APS. The whole processing can be easily parallelized. Results over simulated data are shown. © 2013 IEEE.

  • Track Detection in Railway Sidings Based on MEMS Gyroscope Sensors

     Broquetas Ibars, Antoni; Comeron Tejero, Adolfo; Gelonch Bosch, Antoni; Fuertes Armengol, José Mª; Castro, Jose Antonio; Felip, Damià; López, Miguel Angel; Pulido, Jose Antonio
    Sensors
    Vol. 12, num. 12, p. 16228-16249
    DOI: 10.3390/s121216228
    Date of publication: 2012-11-23
    Journal article

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  • Evaluation of the internal calibration methodologies for spaceborne synthetic aperture radars with active phased array antennas

     Makhoul Varona, Eduardo; Broquetas Ibars, Antoni; Lopez Dekker, Paco; Closa, Josep; Saameno, Paula
    IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
    Vol. 5, num. 3, p. 909-918
    DOI: 10.1109/JSTARS.2012.2199087
    Date of publication: 2012-06
    Journal article

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  • SAR Multidimensional para la observación de la tierra: sistemas, procesado y aplicaciones

     Alonso Gonzalez, Alberto; Centolanza, Giuseppe; Monells Miralles, Daniel; López Martínez, Carlos; Mallorqui Franquet, Jordi Joan; Broquetas Ibars, Antoni; Fabregas Canovas, Francisco Javier; Makhoul Varona, Eduardo; Aguasca Sole, Alberto
    Competitive project

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  • 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
    p. 1-2
    DOI: 10.1109/IRMMW-THz.2012.6380141
    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.

  • Ground moving target indication using multi-channel SAR with non-uniform displaced phase centers

     Makhoul Varona, Eduardo; Broquetas Ibars, Antoni; Ruiz Rodon, Josep
    IEEE International Geoscience and Remote Sensing Symposium
    p. 1610-1613
    DOI: 10.1109/IGARSS.2012.6351221
    Presentation's date: 2012-07-24
    Presentation of work at congresses

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    This paper presents an evaluation of a post-Doppler spacetime adaptive Processing (STAP) technique for non-uniformly displaced phase center receivers synthetic aperture radar (SAR). Both theoretical and simulation analysis are carried out in order to prove the ground moving target indication (GMTI) capabilities for specific non-uniformly spaced multichannel configurations on-board a single satellite platform. Simulated SAR data in the maritime scenario show improved performance, specially for small and slow targets, compared to current SAR missions, equipped with just two channels.

  • GEMINI: geosynchronous SAR for Earth monitoring by interferometry and imaging

     Monti Guarnieri, Andrea; Tebaldini, Stefano; Rocca, Fabio; Broquetas Ibars, Antoni
    IEEE International Geoscience and Remote Sensing Symposium
    p. 210-213
    DOI: 10.1109/IGARSS.2012.6351601
    Presentation's date: 2012-07-23
    Presentation of work at congresses

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    In this paper we discuss a preliminary design for a constellation of geosynchronous (GEO) Synthetic Aperture Radars (SAR). The key design concept is to employ one or more pairs of closely-spaced twin receivers flown onboard GEO minisatellites moving with a velocity of few meters per second with respect to the Earth’s surface, so as to form a synthetic aperture on the order of few tenths of kilometers twice a day. The employement of closely-spaced receivers would enable the estimation of the temporal gradient of the tropospheric delay via along track Interferometry, resulting in the possibility to coherently integrate the signal over an aperture time on the order of hours. As a result an area as wide as one thousand kilometers could be imaged while providing: i) continuous temporal coverage at coarse resolution (hundreds of meters); ii) high resolution (few meters) imaging and interferometric capabilities two or more times a day by integrating the signal over few hours, thus ensuring high SNR performance (for stable targets) with a transmitted power com- parable to currently operated spaceborne SARs.

  • Evaluation of state-of-the-art GMTI techniques for future spaceborne SAR systems -simulation validation-

     Makhoul Varona, Eduardo; Broquetas Ibars, Antoni; González, Oriol
    European Conference on Synthetic Aperture Radar
    p. 376-379
    Presentation's date: 2012-04-25
    Presentation of work at congresses

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    This paper presents an evaluation of the state-of-the-art Ground Moving Target Indication (GMTI) techniques in the frame of space-borne Synthetic Aperture Radar (SAR) for vessel detection by means of a flexible SAR-GMTI simulator tool. Among the different GMTI techniques, Displaced Phase Center Antenna (DPCA), Along-Track Interferometry (ATI) and Imaging Space-Time Adaptive Processing (ISTAP) have been evaluated

  • Atmospheric phase screen retrieval from GEOSAR long term acquisition

     Ruiz Rodon, Josep; Broquetas Ibars, Antoni; Monti Guarnieri, Andrea; Rocca, Fabio
    European Conference on Synthetic Aperture Radar
    p. 79-82
    Presentation's date: 2012-04-25
    Presentation of work at congresses

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    In this paper, a GEOSAR mission with typical LEOSAR parameters but longer integration time to increase the received power is presented. Such systems can provide images of large areas with continuous monitoring. The revisit time is reduced to the synthetic aperture integr ation time to reach the desired resolution and SNR require- ments. However, the Atmospheric Phase Screen (APS) ar tefacts must be characterized to compensate the long term atmospheric phase decorrelation. An APS correc tion methodology from short term periodic acquisitions (sub-apertures) of the whole long term synthetic aperture is analysed. Finally, the first results obtained from Ground-Based SAR (GB-SAR) real data are presented to validate the proposed correction method.

  • Approach to velocity and acceleration measurement in the Bi-Directional SAR imaging mode

     Mittermayer, Josef; Prats, Pau; Wollstadt, Steffen; Baumgartner, Stefan; Lopez Dekker, Paco; Broquetas Ibars, Antoni; Makhoul Varona, Eduardo; Krieger, Gerhard; Moreira, Alberto
    IEEE International Geoscience and Remote Sensing Symposium
    p. 5618-5621
    DOI: 10.1109/IGARSS.2012.6352045
    Presentation's date: 2012-07-26
    Presentation of work at congresses

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    This paper presents an initial analysis of the possibilities for velocity and acceleration m easurement with the Bi- Directional SAR imaging mode (BiDi). It comprises single satellite single path acquisitions as well as a constellation of two satellites. The translati onal velocity components into azimuth and range directions are simulated. A BiDi ap- proach for measuring the azimuth velocity from one satellite with one receiving channel is proposed. Image examples acquired with the TerraSAR-X (TSX) and TanDEM-X (TDX) satellites show velocity and acceleration effects on ships and the proposed BiDi ve locity approach is verified. Interferometric fringes were observed on anchoring ships. A first approach into the understanding of rotational effects was achieved by simulation of rotational fringes.

  • Results on spatial-temporal atmospheric phase screen retrieval from long-term GEOSAR acquisition

     Ruiz Rodon, Josep; Broquetas Ibars, Antoni; Makhoul Varona, Eduardo; Monti Guarnieri, Andrea; Rocca, Fabbio
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3289-3292
    DOI: 10.1109/IGARSS.2012.6350601
    Presentation's date: 2012-07-25
    Presentation of work at congresses

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    In this paper, a high integration gain GEOSAR mission for Earth imaging is presented. The spatial-temporal atmospheric decorrelation issues of a long integration time GEOSAR mission must be carefully studied. The feasibility of a GEOSAR mission for Atmospheric Phase Screen retrieval purposes is studied. The raw data received from several hours of acquisition is divided into sub-acquisitions with integration time on the order of the APS decorrelation time. From each sub-matrix, a low-resolution but enough to sample the spatial variations of the atmospheric map is obtained. The simulated results of the APS retrieval from a GEOSAR acquisition are shown at the end of this paper.

  • Signal-to-noise ratio equalization for TOPSAR mode using a nonuniform steering rate

     Ruiz Rodon, Josep; Broquetas Ibars, Antoni; González Arbesú, José María; Closa Dominguez, Josep M.; Labriola, M
    IEEE Geoscience and Remote Sensing Letters
    Vol. 9, num. 2, p. 199-203
    DOI: 10.1109/LGRS.2011.2162578
    Date of publication: 2011-09-15
    Journal article

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    In this letter, an optimized scanning in terrain observation by progressive scan synthetic aperture radar (TOPSAR) mode is studied. A nonuniform steering rate of the radar array antenna in the along-track direction is proposed in order to obtain constant radiometric sensitivity and signal-to-noise ratio. This is achieved owing to the longer integration time of the echoes received at both ends of the antenna azimuth sweep. By optimizing iteratively the array discrete steering rate law, the radiometric impact of the array basic element pattern (subarray pattern) can be accurately compensated. First, simulation results are presented to validate the nonuniform steering TOPSAR.

  • Research & Development of a Simulator for Moving Target Indicator System

     Makhoul Varona, Eduardo; Rius Casals, Juan-manuel; Aguasca Sole, Alberto; O'callaghan Castella, Juan Manuel; Broquetas Ibars, Antoni
    Competitive project

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  • A Ku-band geosynchronous synthetic aperture radar mission analysis with medium transmitted power and medium-sized antenna

     Ruiz, Josep; Broquetas Ibars, Antoni; Monti Guarnieri, Andrea; Rocca, Fabio
    IEEE International Geoscience and Remote Sensing Symposium
    p. 2456-2459
    DOI: 10.1109/IGARSS.2011.6049708
    Presentation's date: 2011-07-24
    Presentation of work at congresses

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    In this paper, the feasibility of a geosynchronous satellite for Synthetic Aperture Radar applications is assessed. The nearly fixed position of geosynchronous satellites offers new features to SAR acquisition such as the continuous monitoring of wide areas with short revisit times. A monostatic dedicated mission, working with moderated antenna sizes and transmitted powers with long integration time (several hours), is firstly presented and the main SAR parameters (PRF selection, power budget, ambiguities) analyzed. The system Point Spread Function is obtained from simulated raw data showing the system spatial resolution in a realistic orbital configuration.

  • 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
    p. 65-68
    DOI: 10.1109/IMWS3.2011.6061889
    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.

  • A geosynchronous synthetic aperture radar mission analysis based on long integration time acquisition and atmospheric correction

     Ruiz, Josep; Broquetas Ibars, Antoni; Monti, Andrea; Rocca, Fabio
    Ka and Broadband Communications Navigation and Earth Observation Conference
    p. 829-836
    Presentation's date: 2011-10-03
    Presentation of work at congresses

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    Differential SAR interferometry with orbital, airborne and ground-based sensors  Open access

     Mallorqui Franquet, Jordi Joan; Aguasca Sole, Alberto; Broquetas Ibars, Antoni; Fabregas Canovas, Francisco Javier; López Martínez, Carlos; Alonso Gonzalez, Alberto; Iglesias Gonzalez, Ruben; Centolanza, Giuseppe; Monells Miralles, Daniel
    SAR Technologies & Applications Congress
    Presentation's date: 2011-05-30
    Presentation of work at congresses

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    • Introduction to Differential Interferometry • Orbital Sensors: ERS, ENVISAT, RADARSAT2, TerraSAR-X. • Airborne Sensors: DLR’s E-SAR • Ground-Based Sensors: UPC’s GB-SAR • Conclusions

  • 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
    p. 1-2
    DOI: 10.1109/irmmw-THz.2011.6105156
    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
    p. 164-167
    DOI: 10.1109/IMWS3.2011.6061865
    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.

  • 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
    p. 1-2
    DOI: 10.1109/irmmw-THz.2011.6104977
    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.

  • Internal calibration strategies for space-borne synthetic aperture radars with active phased array antennas

     Makhoul, Eduard; Broquetas Ibars, Antoni; Closa, Josep; Saameno, Paula
    IEEE International Geoscience and Remote Sensing Symposium
    p. 898-901
    DOI: 10.1109/IGARSS.2011.6049276
    Presentation's date: 2011-07-24
    Presentation of work at congresses

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    This paper proposes an analytical formulation of the instrumental errors in multilevel hierarchic SAR architecture equipped with active phased array antennas. The basis of the study is the derivation of the so called post-calibration errors, which remain as residual error contributions after the application of a dedicated internal calibration procedure. The limitations of the current internal calibration approaches for the-state-of-the-art space-borne SAR missions are analyzed and alternative internal global calibration strategies are proposed to reduce the impact of the post-calibration error. Numerical simulations of instrumental errors are presented to evaluate the different proposed calibration procedures.

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    Measurement of the electromagnetic field backscattered by a fractal surface for the verification of electromagnetic scattering models  Open access

     Ruello, Giuseppe; Blanco Sanchez, Pablo; Iodice, Antonio; Mallorqui Franquet, Jordi Joan; Riccio, Daniele; Broquetas Ibars, Antoni; Franceschetti, Girogio
    IEEE transactions on geoscience and remote sensing
    Vol. 48, num. 4, p. 1777-1787
    DOI: 10.1109/TGRS.2009.2036007
    Date of publication: 2010-04
    Journal article

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    Fractal geometry is widely accepted as an efficient theory for the characterization of natural surfaces; the opportunity of describing irregularity of natural surfaces in terms of few fractal parameters makes its use in direct and inverse electromagnetic (EM) scattering theories highly desirable. In this paper, we present an innovative procedure for manufacturing fractal surfaces and for measuring their scattering properties. A cardboard–aluminum fractal surface was built as a representation of a Weiestrass–Mandelbrot fractal process; the EM field scattered from it was measured in an anechoic chamber. A monostatic radarlike configuration was employed. Measurement results were compared to Kirchhoff approximation and small perturbation method closed-form results that were analytically obtained by employing the fractional Brownian motion to model the surface shape. Matching and discrepancies between theories andmeasurements are then discussed. Finally, fractal and classical surface models are compared as far as their use in the EM scattering is concerned.

  • Estudio de viabilidad de la estimación cuantitativa de parámetros de nieve mediante técnicas de teledetección (EOSWAN)

     Alonso Gonzalez, Alberto; Fabregas Canovas, Francisco Javier; Broquetas Ibars, Antoni; Mallorqui Franquet, Jordi Joan; López Martínez, Carlos
    Competitive project

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  • New European Watcher

     Rius Casals, Juan-manuel; O'callaghan Castella, Juan Manuel; Makhoul Varona, Eduardo; Broquetas Ibars, Antoni
    Competitive project

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  • Feasibility of geosynchronous satellites for synthetic aperture radar remote sensing at Ka-BAND

     Ruiz, Josep; González, Alba; Broquetas Ibars, Antoni; Monti Guarnieri, Andrea; Carcano, Laura; Fideli, Giorgio; Rocca, Fabbio
    Ka and Broadband Communications Navigation and Earth Observation Conference
    Presentation's date: 2010-10-20
    Presentation of work at congresses

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    This document presents the conceptual design and analysis of a Synthetic Aperture Radar (SAR) system based on geosynchronous satellites (GEOSAR) working at Ka-band. These satellites, apparently orbiting in a fixed position relative to the Earth, are affected by slight perturbations of the perfectly geostationary orbits (small inclinations and non zero eccentricities) that may be used to generate a synthetic aperture radar for Earth Observation. The main advantage of GEOSAR is to obtain short revisit pass (daily or less) with local coverage, thus complementary to typical Low Earth Orbit SAR that achieve global coverage but with weekly or monthly revisit times. A further advantage is the look direction, mainly South-North, that is truly complementary to the LEO satellites looking at East-West. The LEO long revisit times prevent the observation of fast dynamic scenarios like natural hazards, disasters, atmosphere, etc. The GEOSAR main characteristics are presented and different configurations are proposed. Some geosynchronous orbit considerations are shown to understand the particularities in the GEOSAR geometry. The compromises between spatial resolution and sensitivity are obtained together with basic operation parameters like Doppler Analysis, power link budget and ambiguities.

  • Active and passive THz systems for short-range imaging applications

     Abril, Jordi; Nova, Enrique; Capdevila Cascante, Santiago; Broquetas Ibars, Antoni; Torres Torres, Francisco; Jofre Roca, Luis
    European Conference on Antennas and Propagation
    p. 1-4
    Presentation's date: 2010-04-13
    Presentation of work at congresses

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    Teraherz subsurface imaging system  Open access

     Nova, Enrique; Abril, Jordi; Guardiola Garcia, Marta; Capdevila Cascante, Santiago; Broquetas Ibars, Antoni; Romeu Robert, Jordi; Jofre Roca, Luis
    European Conference on Antennas and Propagation
    p. 1-5
    Presentation's date: 2010-04-12
    Presentation of work at congresses

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    A subsurface imaging system based on a terahertz time-domain spectrometer (THz-TDS) is described in this paper. The system performance has been simulated in terms of spatial resolution, penetration capabilities and SNR. Moreover, a commercial THz-TDS has been used to perform the proof-of-concept of the described system.

  • Bistatic SAR based on Terrasar-X and ground based receivers

     Broquetas Ibars, Antoni; Fortes Galera, Eduardo M.; Siddique, M. A.; Duque, Sergi; Merlano Duncan, Juan Carlos; Lopez Dekker, Paco; Mallorqui Franquet, Jordi Joan; Aguasca Sole, Alberto
    IEEE International Geoscience and Remote Sensing Symposium
    p. 114-117
    DOI: 10.1109/IGARSS.2010.5652966
    Presentation's date: 2010-07-26
    Presentation of work at congresses

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  • Combined passive and active millimeter-wave imaging system for concealed objects detection

     Abril, Jordi; Nova, Enrique; Broquetas Ibars, Antoni; Torres Torres, Francisco; Romeu Robert, Jordi; Jofre Roca, Luis
    Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2010 35th International Conference on
    p. 1-2
    DOI: 10.1109/ICIMW.2010.5612976
    Presentation's date: 2010-09-06
    Presentation of work at congresses

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  • SABRINA-X: Bistatic SAR receiver for TerraSAR-X

     Broquetas Ibars, Antoni; Mallorqui Franquet, Jordi Joan; Aguasca Sole, Alberto; Merlano Duncan, Juan Carlos; Duque, Sergi
    European Conference on Synthetic Aperture Radar
    Presentation's date: 2010-06-09
    Presentation of work at congresses

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  • Far field condition in passive interferometry for security screening applications

     Torres Torres, Francisco; Abril, Jordi; Nova, E.; Broquetas Ibars, Antoni; Jofre Roca, Luis
    European Conference on Antennas and Propagation
    p. 1-4
    Presentation's date: 2010-04-12
    Presentation of work at congresses

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    This work presents the main geometric constraints that affect the performance of a passive interferometer at 94 GHz for security screening applications by means of a reviewed definition of the Far Field condition in close range detection applications. This new approach allows to easily give, in a first order approximation, the number of antennas, the array size and the target range by using well known far field tools.

  • Antena reflectarray de haz reconfigurable para frecuencias en los rangos de terahercios y de ondas milimétricas

     Encinar, José Antonio; Pérez, Gerardo; Barba, Mariano; Quintana Arregui, Patxi Xabier; Andreas, Morten; Otón, José Manuel; Broquetas Ibars, Antoni; Abril, Jordi; Nova, Enrique
    Date of request: 2010-12-16
    Invention patent

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    Antena reflectarray de haz reconfigurable para frecuencias en los rangos de terahercios y de ondas milimétricas. La antena reflectarray consiste en un agrupamiento plano de celdas desfasadoras (reflectarray) iluminado por un alimentador, que produce un haz colimado o conformado reconfigurable electrónicamente, donde las celdas desfasadoras (3.b) están formadas por varias capas apiladas de elementos conductores (4c,4e,4d,4f) sobre un substrato dieléctrico (7c,7d) alternadas con capas de cristal líquido (5c,5d) y un plano conductor (9). Aplicando tensiones de polarización en los elementos conductores se varía la constante dieléctrica del cristal líquido produciendo un cambio de fase del campo reflejado en cada celda desfasadora, lo que permite realizar un barrido o reconfiguración electrónica del haz. Al incluir varias capas de elementos conductores y de cristal líquido se mejora el ancho de banda y las prestaciones de barrido o reconfiguración del haz. La antena puede aplicarse para satélites de observación, comunicaciones y sistemas de seguridad.

  • UWB Tomographic Radar Imaging of Penetrable and Impenetrable Objects

     Jofre Roca, Luis; Broquetas Ibars, Antoni; Romeu Robert, Jordi; Blanch Boris, Sebastian; Toda, Ap; Fabregas Canovas, Francisco Javier
    Proceedings of the IEEE
    Vol. 97, num. 2, p. 451-464
    DOI: 10.1109/JPROC.2008.2008854
    Date of publication: 2009-02
    Journal article

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  • BLOCKSAT-2: GUIADO Y POSICIONAMIENTO DE TRÁFICO FERROVIARIO CON SEGURIDAD INTRÍNSECA: SISTEMA DE BLOQUEO BASADO EN NAVEGACIÓN X SATÉ

     Comeron Tejero, Adolfo; Gelonch Bosch, Antoni; Jofre Roca, Luis; Romeu Robert, Jordi; Fuertes Armengol, José Mª; Cabestany Moncusi, Joan; Broquetas Ibars, Antoni
    Competitive project

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  • CONCEPTOS AVANZADOS EN TELEDETECCION ACTIVA Y PASIVA DE MICROONDAS: TECNOLOGIA Y APLICACIONES

     Torres Torres, Francisco; Aguasca Sole, Alberto; Duffo Ubeda, Nuria; Mallorqui Franquet, Jordi Joan; Broquetas Ibars, Antoni; Corbella Sanahuja, Ignasi; López Martínez, Carlos; Fabregas Canovas, Francisco Javier
    Competitive project

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  • Bistatic interferometry using fixed receiver configurations

     Duque Biarge, Sergio; Lopez Dekker, Paco; Merlano Duncan, Juan Carlos; Mallorqui Franquet, Jordi Joan; Broquetas Ibars, Antoni
    European Conference on Synthetic Aperture Radar
    p. 1-4
    Presentation of work at congresses

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  • Synthesis, construction and validation of a fractal surface

     Ruello, G; Blanco, P; Iodice, A; Mallorqui Franquet, Jordi Joan; Riccio, D; Broquetas Ibars, Antoni; Franceschetti, G
    IEEE transactions on geoscience and remote sensing
    Vol. 44, num. 6, p. 1403-1412
    DOI: 10.1109/TGRS.2006.870433
    Date of publication: 2006-06
    Journal article

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  • European Master of Research on Information and Communication Technologies

     Broquetas Ibars, Antoni
    MSc Seminar (Masters Europeus) organitzat pel CLUSTER
    Presentation of work at congresses

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  • Performance Study of Quantized Linear Frequency Modulated signals and its application to CW radars

     Aguasca Sole, Alberto; Broquetas Ibars, Antoni
    3rd European Radar Conference
    p. 100-103
    Presentation of work at congresses

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  • European Master of Research on Information and Communication Technologies

     Broquetas Ibars, Antoni
    MSc Seminar (Masters Europeus) organitzat pel CLUSTER
    Presentation's date: 2006-05-19
    Presentation of work at congresses

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  • Polarimetric SAR interferometry simulator of complex targets

     Margarit, G; Fabregas Canovas, Francisco Javier; Mallorqui Franquet, Jordi Joan; Pipia, L; Borquetas, T; Broquetas Ibars, Antoni
    IEEE International Geoscience and Remote Sensing Symposium
    p. 1-4
    Presentation of work at congresses

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  • Benvinguda als assistents

     Broquetas Ibars, Antoni
    International Conference on Electromagnetic Near-Field Characterization & Imaging
    Presentation's date: 2005-06-08
    Presentation of work at congresses

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  • Temporal Decorrelation in Polarimetric Diffenrential Interferometry using a Ground-Based SAR Sensor

     Pipia, L; Aguasca Sole, Alberto; Fabregas Canovas, Francisco Javier; Mallorqui Franquet, Jordi Joan; Lopez, C; Broquetas Ibars, Antoni
    IEEE International Geoscience and Remote Sensing Symposium
    p. 1-4
    Presentation of work at congresses

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