Ponències/Comunicacions de congressos
http://hdl.handle.net/2117/659
2016-12-07T06:40:24ZConstraints in azimuth resolution by refocusing slowly moving targets from single-look complex SAR vignettes
http://hdl.handle.net/2117/96571
Constraints in azimuth resolution by refocusing slowly moving targets from single-look complex SAR vignettes
Yam Ontiveros, Luis Eduardo; Mallorquí Franquet, Jordi Joan; Rius Casals, Juan Manuel
Accessing the raw data of spaceborne SAR systems is not always possible to refocus blurred SAR signatures of vessels. Instead, the single-look complex (SLC) data is usually more available, but since the vessel motion can shift the Doppler centroid frequency there can be a partial suppression of the target's spectrum during the windowing in the image formation, limiting the achievable azimuth resolution of the SAR signature. Simulations of slowly moving point-targets and complex vessels with spaceborne SAR sensors (C- and X-band) are carried out to examine the impact of the target motion on the azimuth resolution of its SAR signature.
2016-11-11T15:36:31ZYam Ontiveros, Luis EduardoMallorquí Franquet, Jordi JoanRius Casals, Juan ManuelAccessing the raw data of spaceborne SAR systems is not always possible to refocus blurred SAR signatures of vessels. Instead, the single-look complex (SLC) data is usually more available, but since the vessel motion can shift the Doppler centroid frequency there can be a partial suppression of the target's spectrum during the windowing in the image formation, limiting the achievable azimuth resolution of the SAR signature. Simulations of slowly moving point-targets and complex vessels with spaceborne SAR sensors (C- and X-band) are carried out to examine the impact of the target motion on the azimuth resolution of its SAR signature.Pixel reconfigurable antennas: towards low-complexity full reconfiguration
http://hdl.handle.net/2117/93034
Pixel reconfigurable antennas: towards low-complexity full reconfiguration
Rodrigo López, Daniel; Romeu Robert, Jordi; Cetiner, Bedri Artug; Jofre Roca, Lluís
The explosive growth of wireless communications has brought new requirements in terms of compactness, mobility and multi-functionality that make reconfigurable antennas excellent candidates for future wireless networks. Pixel antennas are particularly interesting due to their ability to dynamically reshape its active surface to change
their properties. Despite their outstanding reconfigurability, pixel antennas require a level of complexity and cost that prevents their implementation in commercial systems. In this paper we cover the main concepts for the design and optimization of pixel antennas and propose novel pixel architectures. These new pixel structures allow us to reduce the antenna complexity, maximize their reconfigurability and eventually contribute to the development of pixel antennas
from a conceptual structure to a practical reconfigurable architecture.
2016-11-07T14:16:26ZRodrigo López, DanielRomeu Robert, JordiCetiner, Bedri ArtugJofre Roca, LluísThe explosive growth of wireless communications has brought new requirements in terms of compactness, mobility and multi-functionality that make reconfigurable antennas excellent candidates for future wireless networks. Pixel antennas are particularly interesting due to their ability to dynamically reshape its active surface to change
their properties. Despite their outstanding reconfigurability, pixel antennas require a level of complexity and cost that prevents their implementation in commercial systems. In this paper we cover the main concepts for the design and optimization of pixel antennas and propose novel pixel architectures. These new pixel structures allow us to reduce the antenna complexity, maximize their reconfigurability and eventually contribute to the development of pixel antennas
from a conceptual structure to a practical reconfigurable architecture.Análisis de antenas de reflector mediante procesado gráfico
http://hdl.handle.net/2117/88574
Análisis de antenas de reflector mediante procesado gráfico
Vall-Llossera Ferran, Mercedes Magdalena; Salazar, C; Rius Casals, Juan Manuel; Cardama Aznar, Ángel
The aim of this article is to show a new technique for calculating the Radiation Pattern of arbitrary geometry reflector antennas. We use the Graphical processing technique developed in this group for Radar Cross Section Analysing [1] to obtain the whole geometry information of the reflector antenna necessary to obtain his radiation pattern. This program can obtain the first contribution using Phisical Optics technique, but also can obtain second order contribution.
2016-07-06T15:15:30ZVall-Llossera Ferran, Mercedes MagdalenaSalazar, CRius Casals, Juan ManuelCardama Aznar, ÁngelThe aim of this article is to show a new technique for calculating the Radiation Pattern of arbitrary geometry reflector antennas. We use the Graphical processing technique developed in this group for Radar Cross Section Analysing [1] to obtain the whole geometry information of the reflector antenna necessary to obtain his radiation pattern. This program can obtain the first contribution using Phisical Optics technique, but also can obtain second order contribution.Cálculo de radiación en 3 dimensiones mediante el método de los elementos de contorno
http://hdl.handle.net/2117/88569
Cálculo de radiación en 3 dimensiones mediante el método de los elementos de contorno
Duffo Ubeda, Núria; Rius Casals, Juan Manuel; Cardama Aznar, Ángel
In order to analize the electromagnetic fields generated by perfectly conducting bodies whichever it is its geometry, the Boundary Element Method is applied.
The basic formulation and associated items (integral equations to solve, surface and thin wire discretization, fields interpolation and numerical integration) are comented.
Results of problems of radiation are given and compared with available analytic solutions, which demostrate the good accurancy of the method.
2016-07-06T14:28:17ZDuffo Ubeda, NúriaRius Casals, Juan ManuelCardama Aznar, ÁngelIn order to analize the electromagnetic fields generated by perfectly conducting bodies whichever it is its geometry, the Boundary Element Method is applied.
The basic formulation and associated items (integral equations to solve, surface and thin wire discretization, fields interpolation and numerical integration) are comented.
Results of problems of radiation are given and compared with available analytic solutions, which demostrate the good accurancy of the method.Algoritmo iterativo de propagación espectral para el cálculo de RCS en cavidades conductoras
http://hdl.handle.net/2117/88568
Algoritmo iterativo de propagación espectral para el cálculo de RCS en cavidades conductoras
Rius Casals, Juan Manuel; Cardama Aznar, Ángel; Jofre Roca, Lluís
One of the most difficult problems in the RCS prediction of a complex target is the analysis of the cavities existing at the air inlets and outlets of engines. The geometrical complexity of these structures makes difficult the analysis by modal, ray or beam techniques, while their huge electrical size makes computationally prohibitive the analysis by matrix methods. For these reasons, we have developed an iterative spectral propagation algorithm which can be used to calculate the RCS of electrically intermediate or large cavities with certain geometrical features.
2016-07-06T14:15:41ZRius Casals, Juan ManuelCardama Aznar, ÁngelJofre Roca, LluísOne of the most difficult problems in the RCS prediction of a complex target is the analysis of the cavities existing at the air inlets and outlets of engines. The geometrical complexity of these structures makes difficult the analysis by modal, ray or beam techniques, while their huge electrical size makes computationally prohibitive the analysis by matrix methods. For these reasons, we have developed an iterative spectral propagation algorithm which can be used to calculate the RCS of electrically intermediate or large cavities with certain geometrical features.Caracterización electromagnética de materiales RAM mediante medidas en espacio libre
http://hdl.handle.net/2117/88567
Caracterización electromagnética de materiales RAM mediante medidas en espacio libre
Blanch Boris, Sebastián; Cardama Aznar, Ángel; Jofre Roca, Lluís
A free-space measurement system in the 2-JBGHz frequency range is used to measure the reflection and transmission coefficients of planar samples. The complex electric permittivity and the magnetic permeability are calculated from the measured values of S11 and S21. The measurement system consists of broadband transmit and receive antennas, a network analyzer, mode transitions, and a computer. Error due to multiple reflections between antennas via the swjace of the sample are corrected by using a free space T.R.L. calibration technique.
2016-07-06T14:06:32ZBlanch Boris, SebastiánCardama Aznar, ÁngelJofre Roca, LluísA free-space measurement system in the 2-JBGHz frequency range is used to measure the reflection and transmission coefficients of planar samples. The complex electric permittivity and the magnetic permeability are calculated from the measured values of S11 and S21. The measurement system consists of broadband transmit and receive antennas, a network analyzer, mode transitions, and a computer. Error due to multiple reflections between antennas via the swjace of the sample are corrected by using a free space T.R.L. calibration technique.Diseño de un alimentador primario para dos frecuencias y dos polarizaciones
http://hdl.handle.net/2117/87945
Diseño de un alimentador primario para dos frecuencias y dos polarizaciones
Ferrando Bataller, Miquel; Jofre Roca, Lluís
Primary feeds have been designed to operate simultaneously in two frecuency bands and two cross-polarizations. The multimode generalized scattering matrix has been used to characterize the circular waveguide discontinuity. Input impedance of coaxial line to circular waveguide feed has been computed.
2016-06-13T14:30:05ZFerrando Bataller, MiquelJofre Roca, LluísPrimary feeds have been designed to operate simultaneously in two frecuency bands and two cross-polarizations. The multimode generalized scattering matrix has been used to characterize the circular waveguide discontinuity. Input impedance of coaxial line to circular waveguide feed has been computed.Algoritmos de tomografía de microondas para objetos de alto contrastre
http://hdl.handle.net/2117/87936
Algoritmos de tomografía de microondas para objetos de alto contrastre
Broquetas Ibars, Antoni; Ferrando Bataller, Miquel; Jofre Roca, Lluís
Conventional first order algorithms used in microwave tomography often fail to reconstruct biological bodies due to their high contrast in permittivity. The paper presents several methods to improve the applicability of the algorithms and new reconstruction procedures suitable to high diffracting bodies, using optimization, frequency diversity, analytical continuation and matched plane wave synthesis techniques. The validity of the proposed algorithms is investigated by numerical simulations and experimentally.
2016-06-13T14:07:54ZBroquetas Ibars, AntoniFerrando Bataller, MiquelJofre Roca, LluísConventional first order algorithms used in microwave tomography often fail to reconstruct biological bodies due to their high contrast in permittivity. The paper presents several methods to improve the applicability of the algorithms and new reconstruction procedures suitable to high diffracting bodies, using optimization, frequency diversity, analytical continuation and matched plane wave synthesis techniques. The validity of the proposed algorithms is investigated by numerical simulations and experimentally.Formación de imagen por microondas mediante agrupamientos lineales ortogonales
http://hdl.handle.net/2117/87931
Formación de imagen por microondas mediante agrupamientos lineales ortogonales
Jofre Roca, Lluís; Ferrando Bataller, Miquel; Bolomey, Jean Charles
Capabilities of a microwave imaging system working in the air by using two crossed linear arrays are described. The analytic expressions of the focalization procedures are derived and resolution and available volume of reconstruction are discussed. Finally, some experimental images corresponding to two dielectric objects are also shown.
2016-06-13T13:45:53ZJofre Roca, LluísFerrando Bataller, MiquelBolomey, Jean CharlesCapabilities of a microwave imaging system working in the air by using two crossed linear arrays are described. The analytic expressions of the focalization procedures are derived and resolution and available volume of reconstruction are discussed. Finally, some experimental images corresponding to two dielectric objects are also shown.Análisis y medida en campo próximo de antenas parabólicas
http://hdl.handle.net/2117/87929
Análisis y medida en campo próximo de antenas parabólicas
Jofre Roca, Lluís; Ferrando Bataller, Miquel
A complet process of design and measurement of parabolic antennas, is presented. We have implemented a set of programs in order to design and analyze the different geometries of parabolic reflectors.
The measurements are made on a near field cylindrical system. Finally the most recent studies on antenna metrology and the definition of a semicompact cylindrical field are shown.
2016-06-13T13:41:19ZJofre Roca, LluísFerrando Bataller, MiquelA complet process of design and measurement of parabolic antennas, is presented. We have implemented a set of programs in order to design and analyze the different geometries of parabolic reflectors.
The measurements are made on a near field cylindrical system. Finally the most recent studies on antenna metrology and the definition of a semicompact cylindrical field are shown.