Ponències/Comunicacions de congressos
http://hdl.handle.net/2117/654
2024-03-28T10:49:15Z
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SMOS instrument performance after more than 11 years in orbit
http://hdl.handle.net/2117/367519
SMOS instrument performance after more than 11 years in orbit
Martín Neira, Manuel; Oliva, Roger; Onrubia Ibáñez, Raul; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Rubino, Roselena; Kainulainen, Juha; Closa Soteras, Josep; Zurita Campos, Alberto M.; del Castillo, Javier
ESA's Soil Moisture and Ocean Salinity (SMOS) mission [1] has been in orbit for over 11 years, and its Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) in two dimensions keeps being fully operational. This II-year long lifetime of SMOS, so far, has enabled the calibration and Level-1 processor team to improve the calibration procedures and the image reconstruction resulting in a new version of the Level-1 data processor, v724. To present the main performance features of this new version and the improvement in the calibration procedures constitute the main objective and content of this presentation.
2022-05-19T09:12:58Z
Martín Neira, Manuel
Oliva, Roger
Onrubia Ibáñez, Raul
Corbella Sanahuja, Ignasi
Duffo Ubeda, Núria
Rubino, Roselena
Kainulainen, Juha
Closa Soteras, Josep
Zurita Campos, Alberto M.
del Castillo, Javier
ESA's Soil Moisture and Ocean Salinity (SMOS) mission [1] has been in orbit for over 11 years, and its Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) in two dimensions keeps being fully operational. This II-year long lifetime of SMOS, so far, has enabled the calibration and Level-1 processor team to improve the calibration procedures and the image reconstruction resulting in a new version of the Level-1 data processor, v724. To present the main performance features of this new version and the improvement in the calibration procedures constitute the main objective and content of this presentation.
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X-parameters based characterization of PIN diodes for reconfigurable antenna assessment
http://hdl.handle.net/2117/362347
X-parameters based characterization of PIN diodes for reconfigurable antenna assessment
Ramírez Arroyave, Germán Augusto; Barlabe Dalmau, Antoni; Pradell i Cara, Lluís; Jofre Roca, Lluís
This contribution presents the non-linear characterization up to 50 GHz of a PIN diode commonly used as switch for reconfigurable devices at microwave applications. Non-linear models are extracted by means of X-parameter measurements supported on accurate calibration and de-embedding procedures. Results are validated by S-parameter measurements in the low power signal regime and by harmonic measurements in the large signal regime. The use of these models for reconfigurable antennas assessment is discussed.
2022-02-14T14:33:51Z
Ramírez Arroyave, Germán Augusto
Barlabe Dalmau, Antoni
Pradell i Cara, Lluís
Jofre Roca, Lluís
This contribution presents the non-linear characterization up to 50 GHz of a PIN diode commonly used as switch for reconfigurable devices at microwave applications. Non-linear models are extracted by means of X-parameter measurements supported on accurate calibration and de-embedding procedures. Results are validated by S-parameter measurements in the low power signal regime and by harmonic measurements in the large signal regime. The use of these models for reconfigurable antennas assessment is discussed.
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RF characterisation of new coatings for future circular collider beam screens
http://hdl.handle.net/2117/359537
RF characterisation of new coatings for future circular collider beam screens
Krkotic, Patrick; Pérez, Francis; Pont Montaner, Montserrat; Tagdulang, Nikki; Calatroni, Sergio; O'Callaghan Castellà, Juan Manuel; Granados García, Xavier; Gutiérrez Royo, Joffre; Puig Molina, Teresa; Romanov, Artur; Telles, Guilherme; Hannah, Adrian N.; Malyshev, Oleg; Valizadeh, Reza; Whitehead, David J.
For the future high energy colliders being under the design at this moment, the choice of a low surface impedance beam screen coating material has become of fundamental importance to ensure sufficiently low beam impedance and consequently guaranteed stable operation at high currents. We have studied the use of high-temperature superconducting coated conductors as possible coating materials for the beam screen of the FCC-hh. In addition, amorphous carbon coating and laser-based surface treatment techniques are effective surface treatments to lower the secondary electron yield and minimise the electron cloud build-up. We have developed and adapted different experimental setups based on resonating structures at frequencies below 10 GHz to study the response of these coatings and their modified surfaces under the influence of RF fields and DC magnetic fields up to 9¿T. Taking the FCC-hh as a reference, we will show that the surface resistance for REBCO-CCs is much lower than that of Cu. Further we show that the additional surface modifications can be optimised to minimise their impact on the surface impedance. Results from selected coatings will be presented.
2022-01-13T09:53:33Z
Krkotic, Patrick
Pérez, Francis
Pont Montaner, Montserrat
Tagdulang, Nikki
Calatroni, Sergio
O'Callaghan Castellà, Juan Manuel
Granados García, Xavier
Gutiérrez Royo, Joffre
Puig Molina, Teresa
Romanov, Artur
Telles, Guilherme
Hannah, Adrian N.
Malyshev, Oleg
Valizadeh, Reza
Whitehead, David J.
For the future high energy colliders being under the design at this moment, the choice of a low surface impedance beam screen coating material has become of fundamental importance to ensure sufficiently low beam impedance and consequently guaranteed stable operation at high currents. We have studied the use of high-temperature superconducting coated conductors as possible coating materials for the beam screen of the FCC-hh. In addition, amorphous carbon coating and laser-based surface treatment techniques are effective surface treatments to lower the secondary electron yield and minimise the electron cloud build-up. We have developed and adapted different experimental setups based on resonating structures at frequencies below 10 GHz to study the response of these coatings and their modified surfaces under the influence of RF fields and DC magnetic fields up to 9¿T. Taking the FCC-hh as a reference, we will show that the surface resistance for REBCO-CCs is much lower than that of Cu. Further we show that the additional surface modifications can be optimised to minimise their impact on the surface impedance. Results from selected coatings will be presented.
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Refining the methodology to correct the faraday rotation angle from SMOS measurements
http://hdl.handle.net/2117/345389
Refining the methodology to correct the faraday rotation angle from SMOS measurements
Rubino, Roselena; Duffo Ubeda, Núria; González Gambau, Verónica; Corbella Sanahuja, Ignasi; Durán Martínez, Israel; Torres Torres, Francisco; Martín Neira, Manuel
In this work, a refined methodology to correct the Faraday Rotation angle (FRA) for the SMOS mission is proposed. The method is based on calculating the FRA using the SMOS full-pol radiometric data to obtain VTEC maps applying spatiotemporal filtering techniques, to then making possible the compensation of the FRA effect. By this way, the FRA would be corrected from the data that is measuring the satellite and not using an external database.
2021-05-10T15:38:46Z
Rubino, Roselena
Duffo Ubeda, Núria
González Gambau, Verónica
Corbella Sanahuja, Ignasi
Durán Martínez, Israel
Torres Torres, Francisco
Martín Neira, Manuel
In this work, a refined methodology to correct the Faraday Rotation angle (FRA) for the SMOS mission is proposed. The method is based on calculating the FRA using the SMOS full-pol radiometric data to obtain VTEC maps applying spatiotemporal filtering techniques, to then making possible the compensation of the FRA effect. By this way, the FRA would be corrected from the data that is measuring the satellite and not using an external database.
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Characterization of THz radiation by collimated wavefront aperture raster scanning
http://hdl.handle.net/2117/342877
Characterization of THz radiation by collimated wavefront aperture raster scanning
Nuño Gómez, Daniel-Juan; Santos Blanco, M. Concepción; Gomez Diaz, J. Sebastian; Romeu Robert, Jordi; Jofre Roca, Lluís
We present measurements for characterization of the beam profile and polarization pattern of lens-coupled photoconductive antennas (PCAs) at THz frequencies using a setup with antennas at fixed positions and a movable aperture placed in between collimating THz lenses. The measured beam patterns for co-polar and cross-polar components reveal the expected Airy disc and quadrupole behavior, respectively. The temporal evolution of the polarization in the directions of maximum cross-polar component follows a single-cycle circle with opposite handedness at each side of the antennas line-of-sight (LOS). Results are consistent with those obtained with fiber-coupled movable antennas, while enjoying the simplicity of a free-space laser-PCA feed which does not require painstaking laser realignment for each beam direction measure.
2021-03-30T14:17:38Z
Nuño Gómez, Daniel-Juan
Santos Blanco, M. Concepción
Gomez Diaz, J. Sebastian
Romeu Robert, Jordi
Jofre Roca, Lluís
We present measurements for characterization of the beam profile and polarization pattern of lens-coupled photoconductive antennas (PCAs) at THz frequencies using a setup with antennas at fixed positions and a movable aperture placed in between collimating THz lenses. The measured beam patterns for co-polar and cross-polar components reveal the expected Airy disc and quadrupole behavior, respectively. The temporal evolution of the polarization in the directions of maximum cross-polar component follows a single-cycle circle with opposite handedness at each side of the antennas line-of-sight (LOS). Results are consistent with those obtained with fiber-coupled movable antennas, while enjoying the simplicity of a free-space laser-PCA feed which does not require painstaking laser realignment for each beam direction measure.
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Technology developments for an advanced L-band radiometer mission
http://hdl.handle.net/2117/340437
Technology developments for an advanced L-band radiometer mission
Martín Neira, Manuel; Catalán Artigas, Albert; Corbella Sanahuja, Ignasi; Durán Martínez, Israel; Duffo Ubeda, Núria
ESA’s Soil Moisture and Ocean Salinity (SMOS) mission was launched 2 Nov 2009 and, to date, is still in good health, providing valuable L-band observations of the Earth surface [1]. A number of products are obtained from these, including thin sea ice [2], frost/thaw soils [3], high winds [4], ocean surface wind [5] and Sun brightness temperature [6], besides the main mission measurements of soil moisture and sea surface salinity [7][8]. This paper deals with the description and early results of some technology activities conducted by ESA applying the lessons learnt by SMOS and in preparation of an advanced L-band radiometer mission
© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
2021-02-24T11:48:40Z
Martín Neira, Manuel
Catalán Artigas, Albert
Corbella Sanahuja, Ignasi
Durán Martínez, Israel
Duffo Ubeda, Núria
ESA’s Soil Moisture and Ocean Salinity (SMOS) mission was launched 2 Nov 2009 and, to date, is still in good health, providing valuable L-band observations of the Earth surface [1]. A number of products are obtained from these, including thin sea ice [2], frost/thaw soils [3], high winds [4], ocean surface wind [5] and Sun brightness temperature [6], besides the main mission measurements of soil moisture and sea surface salinity [7][8]. This paper deals with the description and early results of some technology activities conducted by ESA applying the lessons learnt by SMOS and in preparation of an advanced L-band radiometer mission
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Optical beam steering network with multiband capability
http://hdl.handle.net/2117/336740
Optical beam steering network with multiband capability
Vega, Sara; Nuño Gómez, Daniel-Juan; Santos Blanco, M. Concepción
A multiwavelength (MW) optical true time delay Network (OTTDN) to feed a phased array antenna (PAA) is presented. Beam steering capabilities can be demonstrated when applying MW tuning. A Dual Electrode Mach Zehnder Modulator (DE-MZM) as radio frequency (RF) external modulating stage allows to tune the operative band avoiding severe Chromatic Dispersion (CD) fading to obtain a flattened response. A working example simulation of a 4 elements array at 8 GHz shows the RF multiband spectral flat response potential of the technique, as well as the network conditions needed for beam steering with free-lobe operation.
2021-02-03T08:13:17Z
Vega, Sara
Nuño Gómez, Daniel-Juan
Santos Blanco, M. Concepción
A multiwavelength (MW) optical true time delay Network (OTTDN) to feed a phased array antenna (PAA) is presented. Beam steering capabilities can be demonstrated when applying MW tuning. A Dual Electrode Mach Zehnder Modulator (DE-MZM) as radio frequency (RF) external modulating stage allows to tune the operative band avoiding severe Chromatic Dispersion (CD) fading to obtain a flattened response. A working example simulation of a 4 elements array at 8 GHz shows the RF multiband spectral flat response potential of the technique, as well as the network conditions needed for beam steering with free-lobe operation.
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Deriving VTEC maps from SMOS radiometric data
http://hdl.handle.net/2117/329882
Deriving VTEC maps from SMOS radiometric data
Rubino, Roselena; Duffo Ubeda, Núria; González Gambau, Verónica; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Durán Martínez, Israel; Martín Neira, Manuel
In this work, a new methodology is proposed in order to derive vertical total electron content (VTEC) maps from the radiometric measurements of the Soil Moisture and Ocean Salinity (SMOS) mission as an alternative approach to those based on external databases and models. This approach uses spatiotemporal filtering techniques with optimized filters to be robust against the thermal noise and image reconstruction artifacts present in SMOS images. It is also possible to retrieve the Faraday rotation angle from the recovered VTEC maps in order to correct the effect that it causes in the SMOS brightness temperatures.
2020-10-06T10:20:29Z
Rubino, Roselena
Duffo Ubeda, Núria
González Gambau, Verónica
Corbella Sanahuja, Ignasi
Torres Torres, Francisco
Durán Martínez, Israel
Martín Neira, Manuel
In this work, a new methodology is proposed in order to derive vertical total electron content (VTEC) maps from the radiometric measurements of the Soil Moisture and Ocean Salinity (SMOS) mission as an alternative approach to those based on external databases and models. This approach uses spatiotemporal filtering techniques with optimized filters to be robust against the thermal noise and image reconstruction artifacts present in SMOS images. It is also possible to retrieve the Faraday rotation angle from the recovered VTEC maps in order to correct the effect that it causes in the SMOS brightness temperatures.
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A 3D printed lens antenna for 5G applications
http://hdl.handle.net/2117/187869
A 3D printed lens antenna for 5G applications
Ballesteros, Christian; Maestre, Marcos; Santos Blanco, M. Concepción; Romeu Robert, Jordi; Jofre Roca, Lluís
A switchable multi-antenna architecture for lens-assisted beamsteering in the Ka-band region allocated for 5G communications (24-30 GHz) is proposed. The radiating elements are bow-tie antennas mounted with a 3D printed high-permittivity dielectric lens (e r = 10). A 5-element array is simulated showing switchable 30° beam steering over a 120° sector with 19 dB maximum gain. Single antenna measurements of a scaled prototype with a Polylactic Acid (PLA) lens (e r = 2.7) show gains around 11 dB, in agreement with projected performances.
© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
2020-05-18T10:22:21Z
Ballesteros, Christian
Maestre, Marcos
Santos Blanco, M. Concepción
Romeu Robert, Jordi
Jofre Roca, Lluís
A switchable multi-antenna architecture for lens-assisted beamsteering in the Ka-band region allocated for 5G communications (24-30 GHz) is proposed. The radiating elements are bow-tie antennas mounted with a 3D printed high-permittivity dielectric lens (e r = 10). A 5-element array is simulated showing switchable 30° beam steering over a 120° sector with 19 dB maximum gain. Single antenna measurements of a scaled prototype with a Polylactic Acid (PLA) lens (e r = 2.7) show gains around 11 dB, in agreement with projected performances.
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A model for photocurrent generation in photoconductive antennas
http://hdl.handle.net/2117/184392
A model for photocurrent generation in photoconductive antennas
López Menchón, Héctor; Revuelta Martinez, Sergio; Santos Blanco, M. Concepción; Romeu Robert, Jordi; Rius Casals, Juan Manuel
The laser-induced current carrier generation and transport under large biasing voltages in photoconductive materials located in electrode gap region of photoconductive antennas is a complex process involving many different phenomena that interact with each other in intricate ways. Given the large biasing voltages employed, a simple model that assumes that the carriers travel along the biasing field lines allows to retain the basic features of the photocarrier generation process. The model is presented in detail and results for a typical interdigitated electrode are shown to well agree with measures found in the literature.
2020-04-23T05:34:34Z
López Menchón, Héctor
Revuelta Martinez, Sergio
Santos Blanco, M. Concepción
Romeu Robert, Jordi
Rius Casals, Juan Manuel
The laser-induced current carrier generation and transport under large biasing voltages in photoconductive materials located in electrode gap region of photoconductive antennas is a complex process involving many different phenomena that interact with each other in intricate ways. Given the large biasing voltages employed, a simple model that assumes that the carriers travel along the biasing field lines allows to retain the basic features of the photocarrier generation process. The model is presented in detail and results for a typical interdigitated electrode are shown to well agree with measures found in the literature.